Patent Publication Number: US-2016234025-A1

Title: System For, And Method Of, Providing The Transmission, Receipt And Content Of An E-Mail Message To A Recipient

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/758,752, filed Apr. 12, 2010, which is a divisional of U.S. application Ser. No. 11/010,234, filed Dec. 7, 2004, now U.S. Pat. No. 7,698,558, which is continuation-in-part of U.S. application Ser. No. 10/719,812, filed Nov. 21, 2003, now U.S. Pat. No. 7,660,989, and which claims benefit of provisional Application No. 60/528,889, filed on Dec. 10, 2003. Applicants claim priority to all of the applications in the chain. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a system for, and method of, providing for the transmission of a message by a server to a recipient of a message from a sender and for subsequently providing for the authentication of the message to the recipient. This invention also relates to a system and method whereby a recipient of an electronic message verifies the origination of a received message and knows that the message has not been altered since it was transmitted from the originator. 
     BACKGROUND OF A PREFERRED EMBODIMENT OF THE INVENTION 
     In recent years e-mail has become an indispensable business tool. E-mail has replaced “snail mail” for many business practices because it is faster, cheaper and generally more reliable. But there remain some mail applications where hard copy is still dominant, such as registered and certified mail. For example, when a letter is sent by certified mail the sender is provided with a receipt to prove that the letter was mailed. A returned registered mail receipt adds the Postal Service&#39;s confirmation that the letter was successfully delivered to the addressee or the addressee&#39;s authorized agent. Additionally, private couriers such as Federal Express® and United Parcel Service® (UPS) provide some type of delivery confirmation. Since every piece of courier mail is, in effect, registered, it is natural for consumers to turn to these services when they want proof of delivery. 
     Many existing e-mail systems and e-mail programs already provide for some form of proof of delivery. For instance, some e-mail systems today allow a sender to mark a message with “request for notifications” tags. Such tags allow a sender to request notification that the message was delivered and/or when the message was opened. When a sender requests delivery notification, the internet e-mail system may provide the sender with an e-mail receipt that the message was delivered to the mail server or electronic in-box of the recipient. The receipt message may include the title of the message, the destination address, and the time of delivery. It may also include (depending on the types of “flags” that are provided and activated in the mailing software) a list of all the internet “stations” that the message passed through en route to its destination. This form of reporting is built into some of the rules and protocols which implement e-mail. Furthermore, when a message is sent with a “read notification” request, the recipient&#39;s e-mail program may send to the sender an e-mail notification that the recipient opened that message for reading. Many electronic mail clients can and do support this kind of reporting; however, internet protocols do not make this mandatory. 
     However, this does not mean that an e-mail sent with a notification request is as effective in all respects as registered mail. People certify and register letters because they want proof of delivery, e.g., proof that can be used in a civil or criminal proceeding, or proof that will satisfy a supervisor or a client or a government agency that a message has been sent, a job has been done, an order placed, or a contract requirement satisfied. 
     A registration receipt from the United States Postal Service (USPS) constitutes proof of delivery because the USPS stands behind it. The receipt represents the Post Office&#39;s confirmation that the letter or package in question was actually delivered to the addressee or his authorized representative. On the other hand, various hurdles exist to an e-mail receipt being admitted and relied upon as persuasive evidence in a court of law as a proof that the message was delivered. After all, the receipt may be just another e-mail message that could have been altered or created by anyone, at any time. 
     There exists a need for an e-mail system and/or method that can provide reliable proof of the content and delivery of an e-mail message in order to take fuller advantage of the convenience and low cost of communicating via e-mail. 
     To meet this need some systems have been established whereby senders may receive third party proof of delivery by enrolling in services whereby: 
     a) The sender transmits an electronic message to a third party together with a list of the document&#39;s intended recipients. 
     b) The third party sends a notification to each of the message&#39;s intended recipients inviting them to visit the third party&#39;s web site where the message can be viewed. 
     c) If the intended recipient visits the third party&#39;s web site to view the message, the third party records this visit so that the sender may know that his message has been read by the recipient. 
     The drawbacks of such systems are manifold. In the first place, they rely essentially on the co-operation of the recipient of the e-mail to collect his or her messages from the third party&#39;s service. But the circumstances in which a sender may want proof of delivery of a message are often ones in which it cannot be assumed that the intended recipient will co-operate in receiving the message. In such cases, e.g. where acknowledging receipt of the message would place a financial or legal burden on the recipient, the recipient can simply ignore the notification that mail is available for him to receive. Note that there is nothing in such a system to guarantee that the intended recipient has received notification of waiting mail. In the second place, such systems are cumbersome and slow to use as compared to regular e-mail insofar as it can require the sender and/or the recipient to connect to a World Wide Web site to send, collect and verify the delivery of each message. Moreover, transmission of documents by such methods may require both sender and receiver to upload and download files to a web site. Finally, because these methods require the third party to retain a copy of the whole of each message until such time as they are collected or expired, the methods can require its provider to devote substantial computational resources to data storage and data tracking over an extended period of time. As an alternative method of providing proof of delivery, some systems provide proprietary e-mail clients or web-browser plug-ins that will notify senders when a message has been received provided that a recipient uses the same e-mail client. The obvious disadvantage of such systems is that they require both sender and recipient to use the same e-mail client. 
     Therefore, there exists a need for an e-mail system/method that (1) can provide reliable proof of the content and delivery of electronic messages, (2) which does not require the compliance or co-operation of the recipient, (3) requires no special e-mail software on the part of sender or recipient, (4) operates with the same or nearly the same convenience and speed of use as conventional e-mail, and (5) can be operated economically by a service provider. 
     In U.S. Pat. No. 7,966,372, filed by Dr. Terrance A. Tomkow and assigned of record to the assignee of record of this application, a system and method are disclosed and claimed for reliably verifying via secure and tamper-proof documentation the content and delivery of an electronic message such as an e-mail. Ideally, the invention disclosed and claimed in U.S. Pat. No. 7,966,372 will give e-mail and other electronic messages a legal status on a par with, if not superior to, that of registered United States mail. However, it is not necessary to the invention that any particular legal status is accorded to messages sent according to the methods taught in U.S. Pat. No. 7,966,372, as the invention provides useful information and verification regardless. 
     The invention disclosed and claimed in co-pending application U.S. Pat. No. 7,966,372 includes an electronic message system that creates and records a digital signature of each electronic message sent through the system. An originator may send a copy of the electronic message to the system or generate the electronic message within the system itself. The system then forwards and delivers the electronic message to all recipients (or to the designated message handlers associated with the recipients), including to addressees and “cc” addressees. Thereafter, the system returns a receipt of delivery to the originator of the electronic message. The receipt includes, among other things: the original message, the digital signature of the message, and a handshaking and delivery history including times of delivery to the recipients and a digital signature of the handshaking and delivery history. To later verify and authenticate information contained in the receipt, the originator or user sends a copy of the message, the digital signature of the message and the receipt to the system. The system then verifies that the digital signature is the digital signature of the original message. The system then sends a letter or provides other confirmation of authenticity verifying that the electronic message has not been altered. 
     The receipt may also include a digital signature of the handshaking and delivery history. The system may verify that this digital signature is a digital signature of the handshaking and delivery history. This provides a further verification that the message has not been altered. 
     The system disclosed and claimed in U.S. Pat. No. 7,966,372 may include a form of e-mail server connected to the internet, which can be utilized in many ways. For instance, individual users can register their electronic messages, such as e-mails, by sending a “carbon copy” (“cc:”) to the system or composing the message within the system itself. For corporate or e-commerce users, these users can change their server to a server incorporating the present invention and have all of their external electronic messages registered, with the option of having the system retain and archive the receipts. The system can accept and verify encrypted electronic messages and manage the electronic messages within and/or outside a “fire wall.” For web-based users, i.e., individuals or corporations using web-based e-mails, such as MSN Hotmail® or Yahoo Mail®, such users could check a box or otherwise set a flag within their e-mail programs to select on a case-by-case basis whether to make the e-mails of record and/or to archive the messages using the system disclosed and claimed in U.S. Pat. No. 7,966,372. 
     The digital signature can be created using known digital signature techniques, such as by performing a hash function on the message to produce a message digest and then encrypting the message digest. Separate digital signatures can be created for the body of the message, any attachments, and for the overall message including the body, the attachments, and the individual message digests. The encrypted message digest provides one type of message authentication or validation code, or secure documentation. Other message authentication and/or validation codes may also be generated and used. 
     In one aspect, the invention disclosed and claimed in U.S. Pat. No. 7,966,372 is a method of providing proof regarding the delivery and content of an electronic message, comprising: receiving from a sender across a computer network an electronic message, the message having a delivery address associated therewith; computing a message digest according to the message; encrypting the message digest; sending the message electronically to a destination corresponding to the delivery address; recording the Simple Mail Transport Protocol (SMTP) or Extended SMTP (ESMTP) dialog which effects the delivery of the message; receiving Delivery Status Notification information associated with the message and the delivery address; providing to the sender an electronic receipt, the receipt comprising: a copy of the message, the encrypted message digest, the (E)SMTP transcripts, and at least a subset of the Delivery Status notification information, and, at a future date, receiving electronically the electronic receipt from the sender, verifying that the encrypted message digest corresponds to the message, and verifying that the message was received by an electronic message handler associated with the delivery address. 
     In another aspect, the invention disclosed and claimed in U.S. Pat. No. 7,966,372 includes a method of verifying delivery of an electronic message, comprising: in a wide area network computer system, receiving an electronic message from a message sender for routing to a destination address; establishing communication with an electronic message server associated with the destination address, the server defining a destination server; querying the destination server to determine whether the destination server supports Delivery Status Notification (DSN) functionality; receiving a response to the query, the query and response together defining an SMTP dialog; requesting Delivery Status notification information from the destination server according to results of the SMTP dialog; transmitting the electronic message to the destination address; receiving DSN information from the destination server with respect to delivery of the electronic message; and providing to the message sender at least a portion of the SMTP dialog, and at least a portion of the DSN information. 
     In yet another aspect, the invention disclosed and claimed in U.S. Pat. No. 7,966,372 includes a method of verifying content of a received electronic message, comprising: receiving the electronic message; generating a digital signature corresponding to the content of the received message; providing the message and the digital signature to a designated addressee; and, at a later time, verifying that the digital signature is the digital signature of the message. 
     In accordance with still another aspect of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, the method includes establishing whether a message was electronically received by a recipient, comprising: providing a message to be dispatched electronically along with a recipient&#39;s address from a sender; creating a signature associated with the message; dispatching the message electronically to the recipient&#39;s address; tracking the message to determine a final Delivery Status of the message dispatched to the recipient&#39;s address; upon receiving final Delivery Status of the message, generating a receipt, the receipt including a copy of the message, the signature, and the final Delivery Status for the message; and providing the receipt to the sender for later establishing that the message was electronically received by the recipient. 
     In accordance with yet another aspect of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, a method is provided for proving that an electronic message sent to a recipient was read, comprising: providing an electronic message along with a recipient&#39;s address; calculating a digital signature corresponding to the electronic message; dispatching the electronic message electronically to the recipient&#39;s address; requesting a Mail User Agent (email client “reading”) notification from the recipient; upon receiving the reading notification, generating a reading receipt, the reading receipt including a copy of the message, the digital signature for the corresponding electronic message, and a second digital signature for the reading receipt from the recipient; and providing the reading receipt for later verification that said message was received by the recipient. 
     The verification discussed in the previous paragraph may be provided by hashing the message to provide a first digital fingerprint and decrypting the digital signature of the message to provide a second digital fingerprint and by comparing the two digital fingerprints. The verification discussed in the previous paragraph may be further provided by hashing the reading receipt from the recipient to provide a third digital fingerprint, by decrypting the digital signature of the reading recipient from the recipient to provide a fourth digital fingerprint and by comparing the third and fourth digital fingerprints. 
     In accordance with another aspect of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, a method is provided for validating the integrity of a purported copy of an electronic message, comprising: receiving the purported electronic message copy, said purported copy including an encrypted message digest associated therewith; decrypting the encrypted message digest; generating a second message digest based on content of the purported copy; and validating the purported copy by comparing the decrypted message digest and the second message digest to determine whether the two message digests match. 
     In accordance with a still further aspect of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, a method is provided for validating a received e-mail, comprising: receiving an electronic receipt, said receipt including a base message and an encrypted message digest; decrypting the encrypted message digest; generating a second message digest from the base message; and validating the e-mail if the decrypted message digest matches the second message digest, wherein the email has been registered using a service such as RPOST&#39;s REGISTERED E-MAIL service. 
     In yet another aspect, the invention disclosed and claimed in U.S. Pat. No. 7,966,372 includes a website at which users can go to send and receive secure messages, with the website host acting as an independent third party which will send and receive the messages and provide secure documentation regarding the content and delivery of the messages. 
     In U.S. Pat. No. 7,966,372, an authentication of a message provided by a sender to a server and sent by the server to a recipient is provided by the server to the sender. In one embodiment, the server transmits the message to a recipient. The message may pass through intermediate stations before it reaches the recipient. These intermediate stations and the times of the transmission to these intermediate stations are recorded. Other intermediate stations between the recipient and the server provide a record of their operations and the time of their operations in passing all of the information relating to the transmission of the message from the server to the recipient and relating to the transmission of the recipient of the message. 
     In U.S. Pat. No. 7,966,372, a server transmits a message from a sender to a recipient. The message may pass through intermediate stations before it reaches the recipient. These intermediate stations, and the time for the transmission of the message to the intermediate stations form a part of the record received at the intermediate station. The intermediate stations receiving this record in the transmission of the record from the recipient, and the times for the transmission of the record to the intermediate stations, are also included in the record received at the server. The server then transmits to the sender this record, the message, the digital signature of the message and the digital signature of the attachment(s) defined by the record(s) of the intermediate stations and the times of the transmissions to the intermediate stations. 
     When the sender wishes to authenticate the message and the file history of the transmission of the message between the sender and the recipient, the sender transmits this information to the server and the server processes this information to provide the authentication. 
     Generally the server is hired by the sender to act as the sender&#39;s agent in transmitting a message electronically to a recipient. Since the server acts as the sender&#39;s agent, the sender is interested in authenticating that the server has transmitted the message properly to the recipient and in authenticating the time of transmission of the message to the recipient. The system and method disclosed and claimed in U.S. Pat. No. 7,966,372 provides these authentications. 
     Sometimes the recipient is interested in authenticating the message transmitted to the recipient and in authenticating the time of the transmission of the message to the recipient. For example, this is important when the sender is a United States or state court, and the recipient is an attorney involved in representing a client in a matter before the courts and the message relates to a document that the attorney has to file on a short time basis in the court. Under such circumstances, the attorney may wish to have the message authenticated promptly and the time of the transmission of the message to the attorney authenticated promptly. As will be appreciated, any system of method addressing this problem should be simple, prompt and reliable. 
     The mostly widely practiced methods for authenticating the authorship and content of electronic messages involve applications of Public Key Cryptography. In such methods the sender of the message computes a digital digest or “hash” of the contents of the message and encrypts this information, together with other information identifying the sender, using the sender&#39;s private encryption key. The encrypted information is included as an attachment to the message. Upon receiving the message the recipient authenticates its authorship and content by applying the sender&#39;s public encryption key to decrypt the attachment and then compares the decrypted digital digest with a digital digest of the received message. 
     There are several shortcomings with this system: 
     The system requires that the recipient possesses software capable of performing the necessary cryptography and possesses the requisite decryption keys. Some of the most commonly used mail clients, e.g., web based mail client, lack this capacity. The method is not universal among e-mail clients. 
     When a message is “digitally signed” in this manner any change to the message however innocent will result in a failure to authenticate. For example, the changes typically introduced into a message by forwarding it from most e-mail clients will change the message&#39;s digest and will result in a failure to authenticate. PKI digital signatures are, in this sense, fragile. 
     Finally, when a message fails to authenticate because it has changed, it is for all practical purposes, impossible for the recipient to know which portion of the message has changed or to reconstruct the original message. The method is not resilient. 
     In contrast the method described below is universal, non-fragile, and resilient. 
     BRIEF DESCRIPTION OF THE INVENTION 
     A server transmits a message and attachments from a sender to a recipient. A hash is provided of (a) the message, (b) an identification of the sender and (c) a hash of the attachments to form a data string. Instructions may be included for the recipient to send a hashed encryption of the string to a website at the server by registered electronic mail which provides options to obtain other electronic advantages. To authenticate the message, the recipient transmits the message, the attachments and the hashed encryption of the string to the server website. The server decrypts and detaches the hashed encryption of the string to provide a first string and hashes the message, the sender identification and the hashed attachments in the first string to form a second string. The server also detaches and hashes the attachments from the message received at the server website to form first hashed attachments and detaches the hashed attachments from the string to form second hashed attachments. When the first and second hashed attachments match and the first and second strings match, the server authenticates the message to the recipient. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Detailed description of the preferred embodiment of the invention will be made with reference to the accompanying drawings: 
         FIG. 1  is a system diagram of a first embodiment of an invention disclosed and claimed in U.S. Pat. No. 7,966,372, in which embodiment outgoing messages are made of record by being transmitted by a special Mail Transport Agent (MTA); 
       FIGS.  2 A 1 ,  2 A- 2 ,  2 B- 1 ,  2 B- 1 ,  2 B- 2 ,  2 B- 3 ,  2 C,  2 D,  2 E- 1 ,  2 E- 2 , and  2 F constitute a representative flow diagram for making an outgoing e-mail of record according to the embodiment of  FIG. 1 ; 
         FIG. 3  is a system diagram of a second embodiment of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, in which embodiment senders may direct a Mail Transport Agent to transmit selected messages through a separate Mail Transport Agent constructed to make the selected messages of record; 
         FIG. 4  is a system diagram of a third embodiment of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, in which embodiment carbon copies (cc&#39;s) of outgoing messages are sent to a special server to be made of record; 
         FIG. 5  is a system diagram of a fourth embodiment of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, in which embodiment users compose outgoing messages to be made of record at a designated website. 
         FIG. 6  is a system diagram of a fifth embodiment of the invention disclosed and claimed in U.S. Pat. No. 7,966,372, in which embodiment users may send e-mails made of record and store receipts from within a Web Based Mail User Agent (MUA); 
         FIGS. 7A and 7B  constitute a flow diagram for validating an e-mail receipt made of record; 
         FIG. 8  is a system diagram of an embodiment of the invention disclosed and claimed in U.S. Pat. No. 7,966,372 for making of record incoming messages; 
         FIG. 9  is a flow diagram in U.S. Pat. No. 7,966,372 for making of record incoming messages; 
         FIG. 10  is a flow diagram in U.S. Pat. No. 7,966,372 for validating received messages made of record; 
         FIG. 11  is a system diagram showing in U.S. Pat. No. 7,966,372 an exemplary use of the system by an e-business to make of record and acknowledge incoming and outgoing communications; and 
         FIG. 12  is a block diagram showing a system and method operative in combination with the systems and methods shown in  FIGS. 1-11  for authenticating to a recipient a message transmitted to the recipient and the time at which the message is transmitted to the recipient. 
         FIG. 13  and  FIGS. 14A and 14B  are flow charts, primarily in block form, of another system for, and another method of, authenticating to a recipient a message transmitted to the recipient, and attachments to the message, and the time at which the message is transmitted to the recipient. 
         FIG. 15  is a block diagram of a system for use with the embodiments shown in  FIGS. 1-14  in providing a transmission of an e-mail as a REGISTERED E-MAIL message when a user presses a “button”. 
         FIG. 16  is a block diagram of a system for use with the embodiment shown in  FIGS. 1-14  in providing a transmission of an encrypted digitally sealed e-mail message when a user presses a “button” and indicates that the user desires the message to be encrypted and digitally sealed. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION 
     This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. The section titles and overall organization of the present detailed description are for the purpose of convenience only and are not intended to limit the present invention. Accordingly, the invention will be described with respect to e-mail messaging systems that use the internet network architecture and infrastructure. It is to be understood that the particular message type and network architecture described herein is for illustration only; the invention also applies to other electronic message protocols and message types using other computer network architectures, including wired and wireless networks. For convenience of discussion, messages that are processed according to the invention disclosed and claimed in U.S. Pat. No. 7,966,372 may be referred to herein as being “made of record” messages. In the discussion which follows, the term “RPost” will refer in general terms to a third party entity which creates and/or operates software and/or hardware implementing the present invention, and/or acts as a third party message verifier. The term is used for convenience of exemplary discussion only and is not to be understood as limiting the invention. 
     I. RPost as Outgoing Mail Server Embodiment 
       FIG. 1  is a system diagram of a first embodiment of the present invention, wherein outgoing e-mails are made of record according to the invention disclosed and claimed in U.S. Pat. No. 7,966,372. In this embodiment, the third party server  14  serves as the primary outgoing Mail Transport Agent (MTA) for a message sender&#39;s Mail User Agent (MUA)  13 . Although message recipient  18  is technically the addressee and is therefore merely the intended recipient or intended destination at this point in time, for simplicity of discussion this entity will be referred to herein as the recipient, addressee, or destination. Note that a single message may have many different destinations and that each of these may be reached through a different MTA. The method of sending messages made of record may divided into three parts: 
     1) Preprocessing: Steps to be taken before a message is transmitted; 
     2) Transmission: The method of delivering messages to addressees; 
     3) Post Processing: Procedures for gathering information about messages after their delivery, the creation of receipts, and the validation of receipts. 
     I.1. Preprocessing 
     On receiving a message for transmission, the third party server  14  will create records in a database for each message that will be used to store such information as: 
     a) the time at which the message was received; 
     b) the names of the attachments of the message; and 
     c) the number of addressees of the message. 
     For each destination of the message, the database will record: 
     a) the name of the destination (if available); 
     b) the internet address of the destination; 
     c) the time at which the message was delivered to the destination&#39;s Mail Server; and 
     d) the Delivery Status of this destination. Recipient Delivery Statuses used by the system will include: 
     Unsent 
     This status indicates that the message has not been sent. 
     Delivered-and-Waiting-for-DSN 
     This status indicates that the message has been delivered to an ESMTP compliant MTA that supports Delivery Status Notification (DSN) so that a success/failure notification can be expected. 
     Delivered 
     This status signifies that the copy of the message sent to this recipient has been successfully delivered to a server that does not support ESMTP DSN. 
     Delivered-to-Mailbox 
     This status signifies that a DSN message has been received which indicates that the copy of the message sent to this recipient was delivered to the mailbox of the recipient. 
     Relayed 
     This status signifies that an MTA DSN has been received which indicates that the copy of the message sent to this recipient has been relayed onward to another server. 
     Undeliverable 
     This status indicates that after repeated attempts RPost has been unable to connect to an MTA to deliver the messages to this recipient. 
     Failed 
     This status signifies that an MTA DSN has been received that indicates a failure to deliver a copy of the message to this recipient. 
     At this time the system will also perform hashing functions on the message&#39;s contents. 
     Third party server  14  employs a hash function and an encryption algorithm. The hash function may be one of any well-known hash functions, including MD2, MD5, the Secure Hashing Algorithm (SHA), or other hash functions which may be developed in the future. Hash algorithms and methods are described in Bruce Schneider, Applied Cryptography: Protocols, Algorithms, and Source Code in C, John Wiley &amp; Sons, Inc. (New York) 1993; Federal Information Processing Standard Publication 180-1 (FIPS PUB 180-1) Secure Hash Standard, National Institute of Standards and Technology; and U.S. Pat. No. 5,530,757 issued to Krawczyk, entitled “Distributed Fingerprints for Information Integrity Verification,” which are hereby incorporated by reference for their teachings of hash functions, encryption, and methods and systems for implementing those functions. Other known or new methods of detecting whether the contents of the message have been altered may be used. 
     A good hash function H is one-way; that is, it is hard to invert where “hard to invert” means that given a hash value h, it is computationally infeasible to find some input x such that H(x)=h. Furthermore, the hash function should be at least weakly collision-free, which means that, given a message x, it is computationally infeasible to find some input y such that H(x)=H(y). The consequence of this is that a would-be forger who knows the algorithm used and the resulting hash value or message digest will nevertheless not be able to create a counterfeit message that will hash to the same number. The hash value h returned by a hash function is generally referred to as a message digest. The message digest is sometimes referred to as a “digital fingerprint” of the message x. Currently, it is recommended that one-way hash functions produce outputs that are at least 128 bits long in order to ensure that the results are secure and not forgeable. As the current state of the art advances, the recommended length for secure hash functions may increase. 
     Third party server  14  computes a message digest for the message body, and a separate message digest for each of the attachments of the message and stores these in a manner in which they may be later included in a receipt for the message. 
     Before the message is altered in the ways that registration will require, a copy of the original message and its attachments are stored in a manner in which they can be later retrieved by the system. 
     The third party server  14  may alter a message in several ways before transmission to the recipient&#39;s MTA. 
     Although such is not necessary to the practice of the invention, the message may be tagged to denote the fact that the message has been made of record, such as by inserting the words “Made of Record” or at the beginning of the “subject” line of the message, by appending a tag such as, “This message has been made of record with RPOST. Visit our web site at www.RPOST.com for additional information.” at the end of the original message or other tagging. Additionally, the tag may contain instructions, World Wide Web addresses, or links that invite and allow the recipient to send a reply made of record to the message by linking to a Web Page from which messages made of record may be composed and sent. 
     Although tagging is optional, the delivered message will generally be referred to herein as the tagged message. 
     Internet protocols provide two forms of receipt for e-mail messages: 
     MTA Notifications 
     These are e-mails that are sent by a recipient&#39;s MTA notifying the nominal sender of the message that various events have occurred. MTAs that conform to the SMTP protocol will typically only send a notification in the event that the mailer cannot deliver a message to the mailbox of the addressee (as might happen if the address is not valid or if the addressee&#39;s mailbox has exceeded its allotted storage quota). 
     With the introduction of the Extended SMTP standard it became possible for sending MTAs to request notices of success and failure in the delivery of messages. These Delivery Status Notifications (DSNs) are e-mails which are sent by a receiving MTA to the nominal sender of the message when certain events occur: e.g., the message has been successfully deposited into the mailbox of the recipient; the message cannot be delivered to the recipient&#39;s mailbox for some reason; the recipient&#39;s message has been relayed on to another server which does not give DSN receipts. 
     Note that only e-mail servers that support the Extended SMTP (ESMTP) protocol support this form of DSN and that support for this function is optional for ESMTP servers and depends on the configuration selected by the server&#39;s administrators. 
     Although DSN is a term that only came into use with the advent of ESMTP, we will, in what follows, use ‘DSN’ to refer to any MTA generated message relating to the status of a received message whether or not it is in conformity to the ESMTP protocol. 
     MUA Notices (Reading Notifications) 
     These are e-mails that are sent to the (nominal) author of a message by the recipient&#39;s Mail User Agent (MUA) (e-mail program) when certain events occur: e.g., the message is opened for reading, or deleted from the system without being read. By internet convention (RFC 1891), no MUA program can be forced to generate such notifications. Whether an MUA will generate these receipts will depend upon the configuration chosen by its user. 
     The third party server  14  will configure and transmit messages in a way that attempts to elicit both MTA DSNs and MUA notices from compliant MTAs and MUAs. In order to elicit a Reading Receipt from compliant MUAs, certain headers are preferably included in the header section of an e-mail message. Different MUAs respond to different headers; hence Server  14  will add several different headers to each message requesting a read notification in a form recognized by various MUAs. These headers all take the form: 
     Header label: user name &lt;user address&gt; 
     For Example: 
     disposition-notification-to: john smith &lt;jsmith@adomain.com&gt; 
     read-notification-to: john smith &lt;jsmith@adomain.com&gt; where ‘john smith’ is the name of the user to whom an MUA notification is to be sent and ‘&lt;jsmith@adomain.com&gt;’ is that user&#39;s interne address. Normally such headers would refer to the author of the message but in the case of the present method the notification should be returned to the third party so that the notification can be processed by the third party. To assure that this is so, Server  14  will insert headers that request that MUA receipts be sent to an address where they can be processed by the third party server, for example: “readreceipt@RPOST.com”. This will direct any compliant recipient MUAs to send their notifications to an RPOST (third party) address for processing. 
     The task of processing returned MUA notifications raises another problem that should be dealt with at this stage. There are no standards governing the format or content of MUA notifications. Often they will quote the subject of the original message and the time of the event (e.g. “opened for reading”) that they are reporting. But even if this information is included in the notification, it is rarely sufficient to uniquely identify the message that prompts it or to identify the author of that message. When the system receives a MUA notification, it should identify the message that prompts it, so as to include the notification information in the receipt that RPost will generate for the sender. Alternatively, the system should reliably identify the sender of the message to which the MUA notification refers so that the notification information can be passed on to the sender in the form of an RPOST Reading receipt (see below). 
     To accomplish the latter goal, the system can take advantage of the fact that internet addresses have two components: a name field and an address field, where the address field is set off by corner quotes “&lt; &gt;”. Most MUAs will include both fields in the destination address of their MUA notifications. In composing its requests for MUA receipts, the RPost system will include the server  14  read receipt-handling address as the address for the notification but will use the address of the original sender in the name field of the header. For example, where the original sender of the message is user John Smith with internet address jsmith@adomain.com, the RPost server  14  will include headers of the form: 
     Disposition-notification-to: jsmith@adomain.com
 
&lt;readreceipts@RPOST.com&gt;
 
This will typically result in the compliant MUA sending a notification to readreceipts@RPOST.com addressed as:
 
     jsmith@adomain.com &lt;readreceipts@RPOST.com&gt; 
     On receipt of such a notification at the address “readreceipts@RPOST.com”, the server can, by parsing the addressee&#39;s field, determine that the notification concerns a message originally sent by jsmith@adomain.com, even if this could not be determined by any examination of the contents of the notification. With this information in hand, the server can then package the contents of the notification in a digitally signed POST (third party) Reading receipt and send the receipt to the address jsmith@adomain.com 
     The third party system will also endeavor to elicit and collect MTA DSN notices generated by recipient MTAs. Since such notifications are sent to the address listed in the “FROM:” field of the message header, the server  14  will alter each message header so that the message is received as “FROM:” a third party address at which DSNs may be processed. 
     However the problem of processing DSNs raises another issue, which should be dealt with at this stage. DSNs do not have any standard content or format; often it is impossible to determine, merely by examining the contents of these e-mails, what message their contents are giving notification of. This problem was supposed to have been addressed for DSNs generated in compliance with the ESMTP protocol by the use of DSN envelope ID numbers (see RFC 1869). According to the protocol, a transmitting MTA can include a reference number along with its request for a DSN. This number would be quoted in any returning DSN, allowing the sender to identify the subject message of the DSN. However, as a matter of fact, many MTAs that report themselves as supporting ESMTP DSN do not return a DSN envelope ID or any other information sufficient to reliably identify the subject message. Finally, even where a DSN does return information sufficient to identify the message it is giving notice of, it often will not contain sufficient information to identify the specific addressee of the message that has prompted the notification. Thus, a single message might be sent to two addressees at a domain; one might be successfully delivered to the addressee&#39;s mailbox; the other, not. The MTA for the domain may report these events in a DSN in ways that provide no way for the recipient of the DSN to determine which addressee was successfully delivered and which was not (as, for example, may happen if the DSN reports the recipient&#39;s addresses as their local alias names rather than by the addresses contained in the original message). 
     The present invention solves this problem in four steps: 
     1) A unique identification number is generated for each outgoing message (e.g. based upon a time stamp). This number is stored in a database. 
     2) The recipients of each message are enumerated and the identifying numbers are stored in a database. 
     3) The message is sent separately to each intended recipient&#39;s MTA. (Even when two recipients have a common domain name and MTA, the server  14  will transmit the message to that MTA in two separate SMTP telnet sessions.) 
     4) When the server  14  transmits the message to a recipient&#39;s MTA it augments the message&#39;s “FROM” field to show the message as having been sent from an address which incorporates the message&#39;s unique ID and the identifying number of the sender. The address also contains a substring (e.g. “rcpt”) that enables the server to identify return messages as DSNs. 
     Thus, a single message denominated “mmyyddss” by the server  14 , from the sender named John Smith, might be sent to its first intended recipient (denominated “a” by the system) with a header reading: 
     From: John Smith &lt;rcptmmddyyssa@RPOST.com&gt; 
     The same message would be sent to the second recipient with a header reading: 
     From: John Smith &lt;rcptmmddyyssb@RPOST.com&gt; 
     Many e-mail MUAs will only display the name of the sender of a message and thus the special address will be unseen by most recipients. 
     The upshot of this form of addressing is that when the recipient MTAs issue DSNs (whether ESMTP compliant or not) they will address those DSNs to different RPost addressees. On receiving these DSNs, the server  14  can identify them as DSN messages by their “RCPT” prefix and, by parsing the addressees, can determine which message and which recipient is the subject of the DSN. 
     The server  14  will alter the ‘FROM’ field of each message to refer to a recipient of the message each time it attempts to transmit the message to that recipient&#39;s MTA. 
     To insure that recipient replies to transmitted messages are directed properly the server  14  will add an explicit “reply-to:” message header into the message listing the original sender&#39;s name and internet address. In the case of the present example this would be: 
     Reply-to: john smith &lt;jsmith@adomain.com&gt; 
     This will lead recipient MUAs to address replies to a received message to the actual sender&#39;s address, rather than the constructed third party address. 
     I.2. Transmission 
     As noted above, it is part of the method that the third party server  14  transmits a separate copy of an outgoing message to each addressee of that message. Moreover the third party server will attempt to make each such delivery through a direct SMTP connection with a mail exchanger (MX) of record for each destination. 
     Note: Each valid internet e-mail address includes an internet domain name or IP address. Each domain name/address has associated with it an e-mail server(s) authorized to receive mail for addresses in that domain. It will be noted that some domains have more than one server. The Domain Name Server responsible for each domain broadcasts the identity of its mail servers across the internet. This information is publicly available and is managed and transmitted in ways that conform to rules and conventions which govern internet e-mail and Domain Name service. 
     Before transmitting a copy of a message to any destination, the third party server  14  will perform an internet Name Server Lookup to identify an MTA associated with the destination&#39;s domain. Having identified the MTA responsible for receiving mail on behalf of a destination address, the system will attempt to open a telnet connection with the destination&#39;s local MTA. 
     It is common practice for internet e-mails to be relayed from MTA to MTA until they reach their final destination. The primary purpose for providing a direct connection between the third party server  14  and the destination&#39;s MTA is so that the third party server can record delivery of the message, (this record taking the form of an SMTP dialogue) with the e-mail server which has proprietary responsibility for receiving e-mail for the recipient domain name. 
     The existence of this record provides helpful evidence that the message was delivered, in much the same way that a registered mail receipt provides evidence of delivery. USPS Registered mail is treated as verifiably delivered if it can be proved to have been delivered to the addressee&#39;s authorized agent (e.g. a secretary, or mail room clerk). In the event of any legal challenge to the evidentiary merit of an RPOST (third party) delivery receipt, it will be recognized that in selecting an internet e-mail service provider, the recipient has authorized that provider to collect electronic messages on his or her behalf. In turn, that service provider has acknowledged its status as the authorized agent for e-mail recipients of that domain name by broadcasting the address of its MTAs as the receptive e-mail servers for this domain. 
     Accordingly, having delivered messages directly to the mail server responsible for receiving the recipient&#39;s e-mail, the third party will have delivered the message to an agent the recipient has legally authorized to receive his mail. By recording the delivery transaction (that transaction taking the form of an SMTP dialogue) the third party message verifier can claim to have proof of delivery to the recipient&#39;s authorized agent. 
     Note that while the method herein described attempts to collect other forms of proof of delivery to each destination, whether or not these attempts succeed will depend upon factors that will not be in the control of the third party message verifier, (e.g. the form of SMTP support deployed on the recipient&#39;s mail server). On the other hand, every successful delivery direct to a recipient&#39;s mail server will always generate an SMTP record. Recording this record allows the third party message verifier to provide proof of delivery to any valid internet destination that complies with the minimum protocols (SMTP) for internet mail. This represents an important advantage of the current method over other methods that might attempt to prove delivery by reliance on ESMTP DSN. 
     Having identified the MTA for a destination of a message, the server  14  will attempt to open an ESMTP connection with the destination MTA by issuing an “EHLO” handshake in compliance with RFC 1869. If SERVER  16  supports ESMTP, it will respond by listing which ESMTP services it supports. 
     If SERVER  16  supports ESMTP, the third party server  14  will first determine if SERVER  16  supports the ESMTP Service “VERIFY”. The Verify service allows a calling SMTP server to determine, among other things, if an address in an MTA&#39;s domain is genuine. If the third party server  14  determines by these means that the address it is attempting to deliver its message to is not valid, it will terminate the connection, cease attempting to deliver a message to this addressee, and record, in its database, the status of this message destination as UNDELIVERABLE. 
     Whatever its result, server  14  will record the ESMTP VERIFY dialogue in a file and store it so that it may be later attached to or included in the Delivery Receipt for this message. It should be noted that, out of concern for security, few ESMTP servers support the VERIFY function. 
     If System  16  does not support the VERIFY method, then server  14  will nevertheless attempt to deliver the message to System  16 . Typically an MTA will accept messages for any address nominally in its domain and will later send a DSN if the address is invalid. 
     The third party server  14  will then attempt to determine if the destination server supports the ESMTP service DSN. If it does, the third party message verifier will transmit the message with a request that SERVER  16  notify the sender of the message with an ESMTP DSN if the delivery to the addressee succeeds or fails. After the successful transmission of the message to this destination the system will record the Delivery Status of this destination as DELIVERED-WAITING-FOR-DSN. 
     If Server  16  replies to the “EHLO” handshake in a way that indicates that it does not support ESMTP, server  14  will issue a “HELO” message to initiate an SMTP connection. If this connection is achieved, server  14  will transmit the message in compliance with the SMTP protocol and will record the Delivery Status of the destination as DELIVERED. 
     Whether the connection is SMTP or ESMTP, server  14  will record the entire protocol dialogue between the two servers. Typically this dialogue will include protocol messages in which, among other things, the destination server identifies itself, grants permission to upload a message for a named recipient, and acknowledges that the message was received. The third party verifier will save the record of this transaction in such way that it may be later retrieved and included in or attached to the Delivery Receipt for this message. 
     For various reasons the third party server may not be able to achieve an SMTP connection with an MTA of a recipient or it may achieve such a connection but be denied permission to transmit the message by the recipient. In that case, if the interne DNS lookup reveals that the destination address is served by multiple MTAs, server  14  will attempt to deliver its message to each of these in turn. Server  14  will continue to attempt to deliver to an appropriate MTA as often as system resources permit. If, after a length of time, the third party server cannot deliver the message to an address, it will mark the status of this recipient of this message as “UNDELIVERABLE” and stop attempting to send this message to this destination address. 
     When server  14  succeeds in transmitting a message to a destination Server that explicitly supports ESMTP DSN, the third party verifier will record the status of this recipient for this message as “DELIVERED-AND-WAITING-FOR-DSN”. 
     When server  14  succeeds in transmitting a message to the destination Server via a connection that does not explicitly support ESMTP DSN, the third party verifier will record the status of this recipient for this message as “DELIVERED.” 
     I.3. Postprocessing 
     DSN Processing 
     MTA DSNs will be returned to server  14  addressed to fictitious addresses in its proprietary domain (e.g., “RPOST.com”), these addresses having been constructed as described above. Server  14  will scan all inbound mail addressed to the domain and detect DSN messages by their identifying substring (e.g. “rcpt”). By parsing these addresses in the manner described above, the system can identify the message and the recipient that has prompted the DSN notification. 
     There is no standard format for DSN messages; neither is there any standard lexicon in which they report their results. To evaluate a received DSN the system should look in the subject line and the body of DSN messages for words and phrases that express the DSN&#39;s meaning. For example, such phrases as “successful delivery” or “delivered to mailbox” or “was delivered” normally signal that the message the DSN concerns was deposited to the mailbox of the destination. When it detects such phrases the System will change the Delivery Status of this destination of the message to “DELIVERED TO MAILBOX”. 
     Phrases such as “could not be delivered”, “fatal error”, “failure” and “unsuccessful” typically signal a DSN that reports a failure by the MTA to deliver the message to the destination. When it detects phrases such as these in the DSN, the system will change the record of the recipient&#39;s Delivery Status to “FAILED”. 
     Though the system always delivers mail to a proprietary MTA for the destination&#39;s domain, these MTAs will sometimes relay the message to a different server (as may be the case, for example, if the receiving MTA sends mail behind a firewall). In this case the DSN will contain such phrases as “relayed” or “relayed onward”. In such cases the system will change the recipient&#39;s Delivery Status to “RELAYED”. 
     Having evaluated the DSN and updated the recipient&#39;s Delivery Status accordingly, the system will save the DSN and any attachments it may contain in such a way that this message(s) may be included in and/or attached to a Delivery Receipt. 
     Message Management 
     From time to time the system will scan each sent message and examine the status of each destination of that message in order to determine if the system has completed processing of that destination&#39;s delivery. The criteria for completion depend upon the destination&#39;s Delivery Status: 
     DELIVERED: This status indicates that a copy of the message for this recipient has been delivered to an MTA that does not support ESMTP DSN. Such an MTA may nevertheless send a form of Delivery Status Notification in the event that the message could not be delivered to the Mailbox of the addressee (as might happen, for example, if the destination address does not correspond to a valid account within the domain). Accordingly, the system will not treat the delivery for such a recipient as completed until a period of time has elapsed since the delivery to the recipient MTA. This time period—typically two to twenty-four hours—represents an estimate of the maximum time required for a majority of servers to return a notification of a failure to deliver and it may be adjusted if the specific destination domain is remote or known to be prompt or tardy in producing such notifications. 
     RELAYED: This status signifies that a DSN has been received that indicates that the recipient MTA has forwarded the message to another MTA that does not support ESMTP DSN. In this case it is nevertheless possible that the MTA to which the message has been delivered will send a notification of failure to deliver in due course. Accordingly recipients with this status are treated as complete under the same conditions as recipients with the status DELIVERED. 
     DELIVERED-AND-WAITING-FOR-DSN: This status indicates that the recipient&#39;s MTA supports ESMTP DSN and that a DSN has been solicited but not yet received. It may sometimes happen that although an MTA identifies itself as supporting this service it will nevertheless not provide DSNs even in the event of successful delivery. Accordingly, the system will regard deliveries to a destination with this status as completed even if no DSN is received after an interval of time. This interval—typically six to twenty-four hours—represents an estimate of the maximum time typically required for a compliant MTA to return a DSN. 
     DELIVERED-TO-MAILBOX: This status indicates that a DSN indicating successful delivery has been received for this recipient and hence the delivery of the message to this destination is completed. 
     FAILED, UNDELIVERABLE: Deliveries to recipients with this status are always treated as complete. 
     When the system finds that delivery to all recipients of a message has been completed the system will construct a Delivery Receipt for the message. 
     Creation of Delivery Receipts 
     Delivery receipts are e-mails sent to the original sender of the made-of-record message. The receipt  20  may contain: 
     1. an identifier for administrative purposes. This identifier may be or may include reference to the sender&#39;s ID and/or the value of the internet Message-ID of the sender&#39;s message as received by the system; 
     2. the date and time at which the receipt was generated; 
     3. the quoted body of the original message together with the e-mail addresses of its intended recipients; 
     4. the date and time at which the third party server received the message; 
     5. a table for each destination listing: 
     (i) the time at which the recipient&#39;s MTA received the message and/or the time at which the system received a DSN report from the recipient&#39;s MTA; 
     (ii) a Delivery Status of the message for that destination. The Delivery Status quoted in a Delivery Receipt is based upon the system&#39;s internal record of the destination&#39;s Delivery Status. They may be transcribed as follows: 
     Deliveries to destinations whose status is FAILED or UNDELIVERABLE will be recorded in the receipt as “failed”. 
     Deliveries to destinations whose status is DELIVERED or 
     DELIVERED-AND-WAITING-FOR DSN will be recorded in the receipt as “delivered to mail server”. 
     Deliveries to recipients whose status is DELIVERED-TO-MAILBOX will be recorded in the receipt as “delivered to mail box”. The purpose of these reports is to accurately apprise the reader of the form of verification of delivery the system has been able to achieve. 
     6. a list of the original attachments of the e-mail together with the separate message digests of those attachments; 
     7. copies of the attachments to the original message, each original attachment being attached as an attachment to the receipt; 
     8. transcripts, summaries, or abstractions of the transcripts of all of the SMTP dialogs involved in the delivery of the message to each destination; 
     9. quotations from the bodies and the attachments of all received DSN reports including whatever details of delivery or disposition of the message that they might reveal; and 
     10. any files that were returned to the system as attachments to DSN reports. 
     All of these separate elements of the receipt may have their own message digests or digital signatures included within the receipt. Additionally, the receipt may include a single overall encrypted message digest or digital signature computed and appended as part of the receipt, thus providing a single message authentication code which could be used to authenticate all of the information contained within the receipt. Since the receipt itself and SMTP dialogs and DSN reports within the receipt contain time-stamps, the receipt includes a non-forgeable record of the message recipient(s), the message content, and the time(s) and route(s) of delivery. 
     MUA Notification Processing 
     MUA Notifications could be collected and incorporated within RPOST Delivery receipts in the same manner as MTA DSNs. However, MTA notifications are typically issued by receiving MTAs within a few hours of delivery whereas MUA Notifications will not be generated, if ever, until the recipient opens his MUA e-mail client and takes some action with respect to the received mail. For this reason, in this embodiment of the invention MUA notifications are collected separately from MTA notifications and reported in “RPOST Reading Receipts” separate from RPOST Delivery Receipts. 
     MUA notifications elicited by message headers constructed in the manner described above will be returned to a common RPOST (third party) address (e.g. “readreceipts@RPOST.com”) and each notification will contain—in the name field of its address—the address of the original sender of this message. Because this is the only information required to generate a reading receipt in the manner described below, the system can deal with MUA notices whenever these notices may arrive and without any need to have stored any information about the original message in its data banks. 
     MUA notices may report, among other things, that a message has been read by a recipient, that a message has been displayed on the recipient&#39;s terminal (whether or not read), that a message has been deleted without having been opened. There is no protocol-governed standard for the content or format of MUA messages. The system could be configured so as to examine the text of MUAs to interpret their reports in the same fashion as the system uses for MTA DSNs. However, in the current embodiment of the invention, MUAs are not evaluated or interpreted by the server  14  but are, instead, passed on to the sender for his own evaluation in a form that can be authenticated by the third party message verifier. To accomplish this the system will create an e-mail message styled as an “RPOST Reading Notice” which may include, among other items: 
     1. subject line of the received MUA notice; 
     2. the body of the received MUA notice quoted as the body of the Reading Notice; 
     3. the received MUA notice included as an attachment; 
     4. any attachment(s) to the received MUA notice included as an attachment(s). 
     5. message digests of the received MUA notice and of any attachment(s) to that notice; 
     6. a date and time stamp; 
     7. an encrypted hash of at least items  5  and  6  providing an authenticatible date stamped digital signature for the document and all of its contents. 
     Receipt Disposition 
     In the case of the current embodiment of the invention, both RPOST (third party) delivery receipts and Reading Notices are sent to the original sender of the made-of-record message. Since these receipts are digitally signed with an encrypted hash (i.e., a digital signature), the third party message verifier can authenticate the information contained in these messages any time they are presented to the third party verifier for this purpose, in the manner described below. This means that once it has transmitted a copy of the receipt to its sender (with instructions to the sender to retain the receipt for his records), the third party verifier has no further need to retain any data concerning the message or its delivery and may expunge all such records from its system. Thus, the third party verifier need not keep any copy of the original message or the receipt. This economy of archival memory gives the present invention an advantage over various prior art message authentication systems that required large amounts of data storage at the service provider side. 
     In this case the burden of retaining receipt data falls on the original sender of the message. Alternatively or additionally, third party verifier may, perhaps for an additional fee, store a permanent copy of the receipt or of some or all receipt data. The receipt or part(s) thereof may be kept on any suitable archival storage devices including magnetic tape, CD ROM, or other storage device types. Additionally or alternatively, the third party verifier may return receipts or parts thereof to a storage system devoted to this purpose within the control of the sender or the sender&#39;s organization. 
     As described above, the third party verifier receipt information includes all of the data from the original sender&#39;s message and its attachments. There are circumstances in which users of the system might not wish to undertake the burden of retaining receipts in their records (e.g., out of fear of accidental data loss) but might also not wish to have the contents of their message in the hands of the third party. Accordingly, the third party might discard the contents of messages but store in its database only such information (e.g. sender, date of composition, message digests, destinations and Delivery Statuses) as might be provided by the third party to authenticate and verify the delivery of a message when presented with a copy of the message retained by the sender. 
     Verification 
     In the event that the originator of a message requires evidence at a later date that an e-mail was sent, delivered, and/or read, the originator presents the receipt(s) for the message to the operators of the system. 
     For example, in order to prove that a particular message was sent from sender  10  to recipient  18 , sender  10  sends to the third party verifier a copy of receipt  20  with a request to verify the information contained within the receipt. This could be done by sending the receipt to a predefined mailbox at the third party, e.g., verify@RPOST.com. The third party then determines whether or not the receipt is a valid receipt. A receipt is a valid receipt if the digital signature matches the remainder of the receipt, and the message digests match the corresponding respective portions of the original message. Specifically, the third party performs the hash function on the various portions of the message including the message body, the attachments, and the overall message including the SMTP dialog and DSN reports, to produce one or more message digests corresponding to the purported message copy. The third party compares the message digests in the purported copy, including the overall message digest, with the message digests which the third party has computed from the purported message copy. The overall message digest can be compared by either decrypting the overall message digest received as the digital signature in the purported receipt, or by encrypting the overall message digest which was calculated from the purported message copy. If the message digests including the digital signature match, then the receipt is an authentic third party-generated receipt. Assuming that a good hash function was used and that the keys used in the cryptographic hash function and the digital signature encryption algorithm have not been divulged to others, it is virtually impossible that the receipt has been “forged” by the person presenting the receipt. That is, the receipt must have been a receipt that was generated by the third party verifier, and therefore the message contained in the receipt, the to/from information, the date and time of delivery, the fact of successful delivery, the route by which the message traveled, and any DSN information contained within the receipt, must be a true copy of that information and is accurate. The third party verifier can then provide authentication, verification, and confirmation of the information contained within the receipt. This confirmation can take the form of an e-mail confirmation, affidavit testimony from employees of the third party verifier familiar with the methods used by the third party, live sworn testimony in depositions and in court, and other forms of testimony. The third party can charge sender  10 , recipient  18 , or any other entity, fees for the various respective confirmation services. The third party can also provide testimony or other confirmation with regard to the non-authenticity of a purported receipt. Testimony may be provided in accordance with Federal Rules of Evidence 901(9), 901(10), 803(6), 803(7), 1001-1004, 1006, 702-706, corresponding state rules of evidence, and other applicable rules. 
     In sum, the system provides reliable evidence based on the testimony of a third party that a particular message having a particular content was sent, when it was sent, who sent it, who received it, when it was opened for reading, and when it was deleted. This evidence can be presented any time a dispute arises regarding the content and delivery of messages, as for example in contract formation, the timing of stock buy or sell orders, and many other applications. The operators of the system can attest to the accuracy of the information contained in the receipt itself without the need for the operators to preserve any record or copy of the information contained in the receipt. 
     A significant advantage of the system is that it can be used by existing MUAs without any change thereto. Because all the computation, encryption, ESMTP interrogation and dialog, DSN report collection, and receipt compilation, are performed by the third party server  14 , none of these functions need to be implemented within any of the user&#39;s equipment. Thus, users can take advantage of the system quickly and easily. 
     In the embodiment of the invention described above, the server  14  makes of record the delivery of all messages passing through it. Alternatively, a server  14  might make of record only those messages having certain destinations (e.g. external to an organization) or from certain senders (e.g. a customer relations group). Alternatively or additionally, the server  14  might make of record only those messages that had distinguishing characters or strings in the subject or body of the message. For example, the server might make of record only messages that the sender had included “(Make of Record)” or “(MR)” in the subject of the message. All other messages might be delivered by the server  14  or some other server function as an ordinary internet MTA. 
     In this embodiment, the third party can raise revenue in a variety of ways. For instance: the third party can charge message sender  10  or her organization a fee on a per-message basis, on a per-kilobyte basis, on a flat fee periodic basis such as monthly, or on a combination of the above. The third party can also charge fees for authenticating and verifying a receipt, with a schedule of charges depending on whether the verification sought is a simple return e-mail, a written affidavit or declaration, sworn fact testimony in deposition or in court, or sworn expert testimony in deposition or in court. If the users opt to have the third party retain copies of the receipts, the third party can charge per item and/or per-kilobyte per month storage fees. 
     II. Flow Diagram for Making of Record an Outgoing Message 
       FIGS. 2A-2G  constitute a flow chart showing an exemplary operation of the first embodiment of the system. Modifying this flow chart to apply to other embodiments is within the skill of one familiar with software and e-mail protocols. 
       FIG. 3A , Pre-processing, illustrates the steps taken with a message before it will be transmitted by the Making of Record Server (the System). 
     To make of record an e-mail message, in step  201  an originator/sender/user creates an e-mail message using any internet Mail User Agent (MUA). Possible MUAs include: (1) client side e-mail programs; (2) server based e-mail programs; (3) web based e-mail services; and (4) HTML forms submitted through web pages. The message may contain attached files as described in the Requests for Comments (RFCs) 822, 2046, and 2047, which are hereby incorporated by reference. RFCs are a series of notes regarding the internet that discuss many aspects of computer communication, focusing on networking protocols, procedures, programs, and concepts. 
     In this embodiment, the system functions as the sender&#39;s outgoing mail server and hence the sender&#39;s message will be directly transferred to the third party server by the sender&#39;s MUA (step  202 ). 
     In step  203 , the system creates a copy of the original message to be stored for later processing. 
     In step  204 , the system creates a record in a database which may include such information as: the time at which the message was received by the server, the names and size(s) of the file attachment(s) of the message, the name (if known) of each destination of the message; the internet address of each destination; the time at which the message was delivered to the destination&#39;s MTA (initially this value is null) and a unit which records the Delivery Status of each destination. 
     In step  205 , the Delivery Status of each destination is set to “UNSENT”. 
     In step  206 , the system generates and stores a message digest or digital signature generated from the message body. 
     In step  207 , the system generates and stores a hash or message digest for each attachment included in the message. 
     In step  208 , the system may create a modified copy of the original message. In this second copy (step  209 ), the original subject line of the message may be amended to indicate that this copy is made of record (e.g. by pre-pending “Made of Record”). 
     In step  210 , a notice that the message is made of record by the system together with links to the system&#39;s Word Wide Web site may be appended to the body of the message. 
     In step  211 , the e-mail headers may be added requesting reading notification in a variety of header formats recognized by various MUAs. The requests for notification direct the return notification to an address associated with the system: for example, “readreceipt@RPOST.com”. These headers will also include the address of the original sender of the message in the name field of the address to which the MUA notification should be sent. 
     Preprocessing having been completed, the system will now transmit a copy of the message to each of its destinations as illustrated in  FIG. 2B . 
       FIG. 2B  illustrates the steps provided to transmit a message made of record. As step  220  indicates, the process provides a separate transmission for each recipient of the message. 
     In step  221 , the system changes the header field of its working copy of the message to show the message as being “FROM:” a sender whose name is the original sender of the message but whose address is an “RPOST.com” address constructed from: 
     a) a string used to identify returning MTA notifications (e.g. “RCPT”); 
     b) a string which uniquely identifies the message being sent; 
     c) a tag which uniquely identifies the destination this copy of the message is being sent to. 
     In step  222 , using the domain name of the destination currently being sent to, the system does a Domain Name Server Mail exchange lookup to find the address of the MTA(s) responsible for collecting mail for addresses in this domain. 
     In step  223 , the system attempts to make a direct telnet connection to the MTA of the destination. If the connection fails, the system will try to make the connection again. Provided that the system has not exceeded a maximum number of retries ( 227 ) for this destination, the system will try to remake the connection perhaps using another MX server for the destination&#39;s domain ( 228 ). 
     If, after a maximum number of retries, the system cannot connect to an MTA for this destination, the system will, as in step  226 , record this destination&#39;s Delivery Status as “UNDELIVERABLE” and cease attempting to deliver this message to this destination. 
     On connecting to the destination&#39;s MTA, the system will begin making a record of its (E)SMTP dialog with the MTA ( 225 ). 
     In step  229 , the system attempts to initiate an Extended SMTP (ESMTP) exchange with the destination MTA by issuing an “EHLO” greeting. 
     If the destination&#39;s MTS supports ESMTP, the system will then ( 230 ) determine if the destination MTA supports the SMTP function VERIFY. If the MTA supports VERIFY, the system will attempt to determine if the destination address is a valid address within the domain ( 231 ). 
     If the address is not valid, then, as in step  232 , the system will record the Delivery Status of this destination as “FAILURE” and will cease attempting to deliver this message to this destination. 
     If the address is valid or if the ESMTP server does not support VERIFY, the system will then ( 233 ) determine if the receiving MTA supports the ESMTP service DSN (Delivery Status Notification). 
     If the MTA does support ESMTP DSN, the system will transmit the message with ESMTP requests to notify the nominal sender of the message of delivery success or failure ( 234 ). Having transmitted the message, the system will record the Delivery Status of this destination as “DELIVERED-AND-WAITING-FOR-DSN” ( 235 ). 
     If the receiving MTA does not support Extended SMTP, the system will transmit the message using SMTP ( 236 ) and record the destination&#39;s status as “DELIVERED” ( 237 ). 
     Having delivered the message, the system will then store the (E)SMTP dialog, recording the delivery in a manner in which it can later be recovered ( 238 ) and attempt to send the message to another destination. 
     Having transmitted a message to its destination(s), the system must perform several functions in order to gather information about the message&#39;s disposition.  FIG. 2C  illustrates the process by which the system processes MTA Notifications returned by recipient MTAs. 
     Because of the format used in the headers of sent messages illustrated in  FIG. 2B  step  221 , MTA message notifications will be delivered to a fictional local address at the server. The system will be able to detect these notifications by a string (e.g. “rcpt”) embedded in their addresses ( 241 ). By parsing the address, as illustrated in  242 , the system can determine which message to which destination prompted the received notification. 
     In step  243 , the system scans the subject line and the body of received MTAs for phrases that indicate whether the MTA is reporting a successful delivery, a failed delivery, or that the message has been relayed to another server. 
     In the event that the process at step  243  reveals that the notification is reporting a successful delivery, the system will, as illustrated in step  245 , change the Delivery Status of the relevant destination of the relevant message to “DELIVERED-TO-MAILBOX”. 
     If the system determines that the MTA notice is reporting a delivery failure, the system will ( 247 ) change the Delivery Status of the relevant destination of the relevant message to “FAILURE”. 
     In the event that the system determines that the MTA notification indicates that the message was relayed to another server, the system will, as illustrated in step  249 , change the Delivery Status of the relevant destination of the relevant message to “RELAYED”. 
     Having processed the MTA Notification, the system will save this message and all of its attachments in such manner that they may be later recalled and used in construction of a receipt for this destination ( 250 ). 
     From time to time, as illustrated in  FIG. 2D , the system will examine the status of each message to determine if the system has recovered all of the MTA notifications it is likely to receive for each destination of message and may hence proceed to construct a receipt for the message. 
     The system will examine the Delivery Status of each destination of the message. 
     If any destination has the Delivery Status “UNSENT”, then the processing of the message is not complete. ( 252 ). 
     If the Delivery Status of a destination is “DELIVERED-AND-WAITING-FOR-DSN”, then the system will not regard the processing for this destination as complete unless, as is illustrated in step  254 , the time since delivery of the message has exceeded the system&#39;s waiting period (e.g. 24 hrs.). 
     If the Delivery Status of a destination is “DELIVERED”, ( 257 ) then the system will regard the processing of this destination as complete provided ( 258 ) that a period of time has elapsed which the operators of the system treat as sufficient to have received notice of delivery failure from the destination&#39;s MTA. (e.g. 2 hours). 
     Any other destination Delivery Status (e.g. “FAILED”, “UNDELIVER-ABLE”, “DELIVERED TO MAILBOX”) is treated as having completed processing. 
     If processing of any of a message&#39;s destinations is not complete the system takes no action but moves to consider other messages in the system (step  255 ). 
     However, as illustrated in step  259 , if processing of every destination of the message is complete, the system will generate a Delivery Receipt for the message. 
     As illustrated by way of example in  FIG. 2E , the receipt may include: 
     An identifier for administrative purposes as in block  271 . This identifier may be, or may include, reference to the sender&#39;s ID and/or the value of the interne Message-ID of the sender&#39;s message as received by the system. 
     As in block  272 , the quoted body of the original message  12  together with the e-mail addresses of its intended recipients may also be included. 
     As in block  273 , a table for each recipient listing may include: 
     a) the time at which the recipient&#39;s MTA received the message and/or the time at which the system received DSN from the recipient&#39;s MTA; 
     b) the Delivery Status report of the message for that destination, i.e., “Delivered to Mail Server”, “Delivered to Mail Box”, “Relayed”, “Delivery Failure”, or “Undeliverable”. 
     As in block  274 , a list of the original attachments of the e-mail together with their separate hash values or message digests. 
     As in block  275 , transcripts or abstractions of the transcripts of all of the SMTP dialogs involved in the delivery of the message to each destination. 
     As in block  276 , quotations from the bodies and the attachments of all received DSNs including whatever details of delivery or disposition of the message that they might reveal. 
     As in block  277 , the system may attach to the receipt copies of all of the attachments of the original message, and, as in block  278 , the system may additionally attach files returned to the system as attachments to DSNs. 
     In step  279 , having generated the text of the receipt so far, the system then generates a first hash for the e-mail message and a second hash(es) for any attachments to the body of the receipt and calculates a digital signature for each of the hash(es) using an encryption key known only to the operators of the system. Encryption can employ, for example, the Data Encryption Standard described in Federal Information Processing Standard Publication 4-2 (FIPS PUB 46-2), the Data Encryption Standard, National Institute of Standards and Technology, which is hereby incorporated by reference. Alternatively, other known or new methods of encrypting the hash value may be used. 
     In step  280 , the encrypted hash is then appended to the end of the message as the “document digital signature”. 
     In step  281 , the receipt  20 , now being complete, may be sent by e-mail to the sender with the advice that it be kept for the sender&#39;s records. In step  282 , the system may now delete all copies of the original message, attachments, and DSNs. Alternatively, rather than sending the receipt to the sender, the system may store the receipt, or both the sender and system can store the receipt. 
     Because MUA notifications are returned only at the option of the recipient and only when the recipient takes some action with respect to the received message, embodiments of the system may choose to treat these return messages differently than MTA notifications. 
       FIG. 2F  illustrates how these MUA notifications may be treated by the system. MUA notifications are solicited by the system by including various headers in outgoing messages in the manner of  FIG. 2A , step  211 . These headers direct compliant MUAs to send notifications to a system address (e.g. “readreceipt@RPOST.com”) set aside for this purpose. The headers also use, in the “name” field of this return address, the e-mail address of the original sender of the message. Accordingly, in step  286 , when MUA notifications are returned to readreceipt@RPOST.com the system can, by examining the address of the notification, determine the address to which a reading notification should be sent. 
     Upon the arrival of a read receipt from a destination&#39;s MUA, the system, in step  287 , generates a reading receipt that contains the subject of the received MUA notification as its subject and incorporates, in its message body, the body of the received MUA Notification. 
     In step  288 , the system attaches to the receipt any files that may accompany the MUA&#39;s receipt (typically these may include details of delivery or disposition and identifying references to the original e-mail.) 
     In step  289 , the system generates a hash for any files attached to the receipt and records this hash in the body of the receipt. 
     In step  290 , the system generates a hash for the body of the receipt and its attachments, encrypts this hash, and appends the result to the message as a “document digital signature”. 
     In step  291 , the system sends the resulting receipt to the sender of the message. In step  292 , having sent this receipt, the system may delete all internal records of the transaction. 
     III. RPost as Secondary Mail Server Embodiment 
       FIG. 3  is a system diagram of a second embodiment of the present invention wherein server  14  does not serve as the user&#39;s primary MTA but rather works in collaboration with another MTA. In this embodiment, the sender may elect to make of record a particular outgoing message by including some form of flag in an outgoing message, message subject, or message addresses. For example, if and only if a sender includes the symbol “(Made of Record)” or “(MR)” in the subject of the message the sender&#39;s MTA will direct the message to be transmitted through server  14  to generate a receipt. 
     In this embodiment the operators of the third party system receive revenues from the operator of the sender&#39;s MTA per message and/or per kilobyte transmitted. 
     IV. CC to RPost Embodiment 
       FIG. 4  is a system diagram of a third embodiment in which a carbon copy (“cc”) is sent to the server  14 . In this embodiment, the user or message sender  10  can use a standard MUA and standard MTA without modification. Message sender  10  composes the e-mail having a message body and any number of attachments, and addresses it to message recipient  18 , along with any carbon copies (cc&#39;s) and blind carbon copies (bcc&#39;s) as desired. Additionally, message sender  10  addresses a cc to the third party system. Server  14  tags the message as before, and sends the tagged message including attachments to the recipient&#39;s MTA  16  and any designated cc&#39;s. On receipt of such a copy server  14  may send an e-mail acknowledging receipt of the copy. 
     Recipient  18  and other destinations of the message will now receive two versions of the same message: a first version of the message received directly from sender  10 , and a second and tagged version which was forwarded from the third party server. Once the third party server receives confirmation from recipient MTA  16  that the tagged version of the message was successfully received by recipient MTA  16 , server  14  composes message receipt  20  as before and sends the receipt to sender  10  for his records. 
     Revenue can be generated by establishing accounts for message originating domains or individual message senders, and charging the users&#39; accounts per message, per kilobyte, per month, or a combination of these. Revenue can also be generated for the placement of advertisements on receipts and from authentication and verification services as previously described. 
     V. Website Embodiment 
       FIG. 5  is a system diagram of a fourth embodiment. In this embodiment, server  14  is associated with a website at which a user composes messages. Message sender  10  visits the third party Website and composes his message at the website by entering the desired “to”, “cc”, “bcc”, “Subject”, and message text information. Attachments can be added by using features available on standard browsers and web servers. In this embodiment, the sender additionally provides an address to which the made-of-record receipt may be sent. Server  14  sends the receipt to sender  10  through sender&#39;s MTA. 
     Revenue can be generated by establishing accounts for message originating domains or individual message senders, and charging the users&#39; accounts per message, per kilobyte, per month, or a combination of these. Revenue can also be generated for the placement of advertisements on receipts and from authentication and verification services as previously described. 
     VI. Web Based MUA Embodiment 
       FIG. 6  is a system diagram of a fifth embodiment. In this embodiment, the server  14  is associated with a web based Mail User Agent. In addition to allowing users to compose mail through a web browser, such a MUA provides subscribers with browser viewable mailboxes that display messages stored on the web server site. Subscribers to such a service gain access to mail accounts with user names and passwords. In this embodiment, message sender  10  visits the RPost website, accesses a web based e-mail account by entering a user name and password, and composes his message which is transported for delivery to server  14 . Receipts generated by the server  14  are returned to a web based mailbox associated with the subscriber&#39;s account. 
     In addition to the revenue sources available in other embodiments, in this embodiment the operators can charge storage fees for receipts held in the web based mailbox. 
     In all of these embodiments, the receipt may serve as evidence that: 
     (1) the originator sent an e-mail message; 
     (2) the message was sent at a certain time; 
     (3) the e-mail was addressed to certain recipient(s); 
     (4) the e-mail was delivered to the e-mail mailbox of each of its intended recipient(s); 
     (5) the e-mail was delivered at a certain time; 
     (6) the e-mail was delivered by a certain network route; and 
     (7) the e-mail message and its attachments had the specific content recorded in the receipt. 
     Furthermore, the system under certain circumstances generates a separate receipt, which may be used as evidence that: 
     (1) the e-mail was inspected through the recipient&#39;s Mail User Agent (MUA); and 
     (2) the recipient took certain actions in response to the message, e.g., read or deleted the e-mail, at a particular time. 
     As with the other embodiments, this embodiment produces documented evidence which may be attested to and verified by the disinterested third party operators of the system concerning the delivery and integrity of an electronic message. In other words, the system can be thought of as transforming the e-mail to a made-of-record e-mail that can later be used to prove that a particular e-mail message was sent, that it was successfully delivered, and when and how. 
     Should a dispute ever arise, the dispute can be resolved through the receipt generated by the system because the receipt is so encoded that the operators of the system can determine the authenticity of the receipt as the product of the system. Thereafter, operators of the system can attest to the accuracy of the information contained in an authentic receipt, relying only on information contained in the receipt itself and without the need for the operators to preserve any record or copy of the information contained in the receipt. 
     In addition to these benefits, the receipts generated by the system may also be useful as evidence of the existence and authorship of such materials as might be transmitted through the system. Moreover, the system is easy to use, as the system can be used from any internet e-mail client program/MUA, so that there is no additional software required. 
     VII. Flow Diagram for Validating a Receipt 
       FIG. 7  is a flow diagram illustrating an exemplary method for validating a receipt. In the event that the sender of a message should require evidence that an e-mail was sent and delivered (and/or read) the sender presents the receipt(s) corresponding to the message to the operators of the system in step  700 . The operators of the system then, in step  702 , detach and decrypt the document digital signature appended to the receipt. In step  703 , the operators generate a hash of the balance of the document, including attachments. 
     In step  704 , if the current hash value does not match the decrypted hash value, then the system generates a report stating that the third party cannot authenticate the receipt as an accurate record of the delivery or the contents of the message described in the receipt. 
     If the decrypted hash is equivalent to the current hash of the message, the system can, as in step  706 , warrant that the information contained in the body of the message is unchanged since the receipt passed through the system. If the original message contained no attachments, the system may now generate a report that warrants that the receipt is an accurate record of the message&#39;s contents and its delivery by the third party server. 
     If the receipt reports that the original message contained attachments, then the receipt will also record the name and hash value of each attachment. In generating the receipt all attachments of the original message are attached unchanged to the receipt. Accordingly, the system will, for each such attached file, generate a hash of the attached file ( 708 ) and compare it to the hash value recorded in the body of the receipt ( 709 ). 
     If the calculated hash value of a file matches the value included in the receipt, the system can warrant that the file attached to the receipt is identical to that attached to the message as originally delivered. If the hashes do not match, then the system will report that it cannot warrant that the file attached to the receipt is identical to the file attached to the original message. 
     Having performed this calculation for each file attached to the original message, the system prepares a report which reports on the authenticity of the receipt and each of its attached files ( 710 ) or which reports the failure of validation ( 712 ). 
     Having completed its evaluation, the system will then append a copy of the receipt and all of its attachments to the report it has generated and send it via e-mail to the return address of the user who submitted the report for validation. 
     VIII. Registering Inbound Emails 
       FIG. 8  is a system diagram illustrating another embodiment of the invention in which incoming e-mails are made of record. In this embodiment, a message sender  60  sends an e-mail message  70 . Sender&#39;s MTA  62  sends message  70  onto the internet as usual. However, in this embodiment the third party contracts with service subscriber/recipient  68  to make incoming e-mails of record. According to the agreement, the third party is designated with Network Solutions, Inc. (NSI) or other domain name authority as the mail recipient (MX server) for recipient  68 . This causes the Domain Name Service (DNS) request performed by the sender&#39;s MTA  62  to return the IP address of the third party as the IP address for the recipient, which in turn causes sender&#39;s MTA  62  to send the e-mail message to server  64 . Server  64  acts as an SMTP, POP, POP3 or IMAP MTA (collectively, “POP mail server”) for recipient  68 . SMTP, POP and IMAP MTAs are governed by RFC 821, the SMTP protocol, RFC 1939 Post Office Protocol—Version 3 (which obsoleted RFC1725), and RFC 2060 IMAP (Internet Message Access Protocol) Version 4 rev 1 (which obsoleted RFC1730), which are hereby incorporated by reference. 
     RPost server  64  prepares a made-of-record version  74  of the original message  70 , and places this made-of-record version  74  into recipient  68 &#39;s in-box instead of, or in addition to, the original message  70 . The made-of-record version may have all of the verification and informational features and options discussed earlier in connection with e-mail receipts. This information can include, but is not limited to: individual message digests for each of the message body and text, the to/from information, other header information, each attachment, an overall message digest and digital signature and message routing information and tags. Made-of-record version  74  of message  70  as shown in  FIG. 6  includes the message body including the header information, an attachment, separate message digests for each, and a digital signature or encrypted message digest. The hash functions and encryption are performed using private phrases or private keys known only to the operators of the system. The made-of-record version  74  is made available to recipient  68  for inspection or downloading through the recipient&#39;s MUA. 
     Server  64  can optionally send a confirming e-mail  72  to message sender  60 . Confirmation message  72  can be a simple text message indicating that a message was received and made of record. Confirmation message  72  could also include a message such as, “Your e-mail message was received on Mar. 24, 2000 at 2:05 p.m. The digital signature of the message was [128-bit digital signature]. For more information, visit our website at www.RPOST.com.” Alternatively, or additionally, confirmation message  72  could include all of the information contained in the made-of-record version  74 . 
     Thus, the system may provide to message recipient  68  a receipt  74  or other verifiable confirmation that: 
     (1) the recipient received an e-mail message; 
     (2) the message was received at a certain time; 
     (3) the e-mail was addressed from a certain sender; 
     (4) the message purports to be delivered via a certain network route; and 
     (5) the e-mail message and its attachments had a specific content. 
     Accordingly, the system provides evidence, which may be attested to by the operators of the system, that particular electronic messages and documents were delivered to recipients having certain content and representing themselves as having come from certain senders. 
     IX. Example of Making of Record in-Bound E-Mail 
       FIG. 9  is a flow chart illustrating one example of making of record in-bound e-mail. In step  901 , server  64  receives a new e-mail message. In step  902 , the system generates a hash/digital signature of the message&#39;s contents including the message&#39;s headers and attachments. Additionally, the system may generate a separate hash for each message attachment. In step  903 , the system encrypts the hash(es) using an encryption key known only to the operators of the system. In step  904 , the resulting encrypted hash(es) is then appended to the body of the message. Then, in step  905 , the modified message may be made available for inspection or downloading through the recipient&#39;s MUA. 
     X. Example of Validating a Received Made-of-Record E-Mail Message 
       FIG. 10  is a flow chart of one example of validating a received made-of-record e-mail message. In step  1000 , in the event that the recipient of a message should require evidence that an e-mail with a specific content was received at a particular time, the recipient can present a copy of the made-of-record version  74  ( FIG. 8 ) of e-mail message  70  to the operators of the system for verification. To verify the message, in step  1001  the system detaches and decrypts the document digital signature appended to the message. In step  1002 , the system generates a hash of the balance of the document, and one for each file attached to the message. In steps  1003  and  1004 , the hashes are compared. If the document hash(es) matches the decrypted hash(es), then the message and its attachments have passed through the system and have not been altered since their delivery to the recipient. 
     Having determined that the e-mail is unaltered, the operators of the system can warrant that: 
     (1) the e-mail was received by the system at a certain time; 
     (2) the e-mail purported to arrive at the system via a certain internet route; 
     (3) the e-mail purported to be from a certain sender; and 
     (4) the e-mail and its attachments were delivered with the specific content they currently contain. On the other hand, in step  1006 , if the hash values do not match, then the operator cannot warrant that the e-mail is authentic, i.e., that the e-mail is an accurate version of an e-mail that was received by the system. 
     XI. How a Business Utilizing Electronic Tools May Use the Invention 
       FIG. 11  illustrates how the invention may be used by a business which utilizes electronic tools (an “e-business”). E-business  30  can utilize the system to make of record all incoming and outgoing e-mail messages from its customers  34 . In this case, the system includes Post Office Protocol (POP) server  36  and Simple Mail Transfer Protocol (SMTP) server  38 . For example, the e-business  30  can set up its website to e-mail forms to customers, and to forward queries and complaints  40  from customers  34 . The made-of-record queries, complaints, orders, offers to purchase, and other information  46  are sent to the e-business  30  by the system. Receipts are then provided to the customers  34  via SMPT server  38 . This way there is no question regarding whether or not the customer sent the communication and what it contained. Moreover, the e-business can set up a web site  32  through the third party server so that every communication with the customers can be made of record. In other words, through the web site form data orders  42  and automated responses  44  can be made of record through the system server; furthermore, any confirmation, collections notices, customer support, and special offers  48  sent by the e-business to customers  34  can be made of record and the confirmation sent to the customer to eliminate arguments about what was ordered, when, or by whom. If desired, identical receipts can be provided to both the customers  34  and to e-business  30 . Alternatively, the functions of POP server  36  and SMTP server  38  may be combined in a single system server. 
     POP is a protocol used to retrieve e-mail from an e-mail server. Many e-mail applications (sometimes called e-mail clients) use the POP protocol, although some can use the newer Internet Message Access Protocol (IMAP). One version of POP, called POP2, requires SMTP to send messages. A newer version, POP3, can be used with or without SMTP. SMTP is a protocol for sending e-mail messages between servers. Many e-mail systems that send e-mail over the internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server. E-mail servers may use a variety of protocols to communicate with the internet. Commonly used protocols include SMTP, POP3 and IMAP4. Mail readers are at the opposite end of the server. Since mail servers receive messages via SMTP, e-mail readers send e-mail to a mail server using SMPT. Likewise, since mail servers send messages using POP3 and optionally IMAP4, mail readers receive messages from mail servers by using the POP3 or IMAP4 protocol. 
     Although the above generally describes a system and method of verifying that an e-mail was sent and/or received, the invention disclosed and claimed in U.S. Pat. No. 7,966,372 may apply to any electronic message that can be transmitted through an electronic message network or through any electronic gate. Electronic messages may include text, audio, video, graphics, data, and attachments of various file types. The methods and techniques taught herein can be programmed into servers and other computers, and computer programs implementing the invention can be written onto computer readable media including but not limited to CD ROMs, RAM, hard drives, and magnetic tape. E-mail made-of-record services according to the present invention can be bundled with internet service provider (ISP) services to provide a single provider ISP solution to corporate and other institutional clients. Implementing the above-described invention is within the skill of the ordinary practitioner of the software arts. 
     XII. System Providing for an Authentication of a Message to a Recipient 
     In the embodiments shown in  FIGS. 1-11 , systems and methods are disclosed for authenticating to a sender a message transmitted by a server on behalf of the sender to the recipient. The authentication relates to (a) the content and wording of the message, (b) the time for the transmission of the message by the server to the recipient and (c) the intermediate stations through which the message is transmitted by the server to the recipient and (d) the intermediate stations through which the validation of the receipt of the message by the recipient is transmitted to the server. The authentication may be provided by producing a digital signature of the message and a digital signature of the attachment(s) to the message, these attachment(s) illustratively relating to the actual events involving the message at each of the intermediate stations or relating to a composite of the factual events at all of the intermediate stations. 
     As will be appreciated, the server is generally paid by the sender. Because of this, the server generally acts as an agent of the sender. To provide for an authentication of the message and the related information to the sender, the server sends to the sender a copy of the message, a digital signature of the message, the attachment(s) including the history of the transmission of the message to the successive intermediate stations between the server and the recipient and a digital signature of this history. The digital history may relate to each intermediate station individually as a separate attachment or may relate to a single attachment involving all of the intermediate stations or any combination of the above. The server does not have to retain any of this information because the sender will provide this information to the server when the sender wishes to obtain an authentication. 
     When the sender wishes to authenticate the message and the transmission of the message from the server to the recipient, the sender transmits to the server all of the information that the server has previously transmitted to the sender. This includes the message, the digital signature of the message, the history of the transmission of the message to the intermediate station(s) between the server and the recipient and the digital signature of this history. The transmission history between the server and the recipient may be considered as a single attachment comprising all of the intermediate stations or may be considered as a plurality of attachments each relating to an individual one, or combination of, of the intermediate stations. 
     To authenticate the message, the server obtains a digital fingerprint (or digital digest) of the message and a digital fingerprint (or digital digest) from the digital signature of the message. The server then compares the two (2) digital fingerprints (or digital digests). If the two (2) digital fingerprints match, the server authenticates the message. To authenticate the transmission history between the server and the recipient, the server produces a digital fingerprint of an attachment comprising the composite transmission history of all the intermediate stations between the server and the recipient (including the server and the recipient) or the transmission history at each, or combinations, of the intermediate stations between the server and the recipient. The server also obtains a digital fingerprint (or digital digest) of the digital signature derived from the attachment or attachments. The server then compares the digital fingerprint(s) of the attachment(s) and the digital fingerprint(s) derived from the digital signature(s) of the attachment(s). If the digital fingerprint(s) match, the server authenticates the transmission file history. The authentication to the sender of the message transmitted from the server to the recipient and the attachments to the message is disclosed and claimed in U.S. Pat. No. 7,966,372, filed in the USPTO on Jul. 27, 2000 by Dr. Terrance A. Tomkow and assigned of record to the assignee of record of this application. 
     In order to authenticate that the message from the sender was transmitted to the recipient, the server authenticates the message and also authenticates the transmission of the message from the server to the recipient through the intermediate stations. If one of the authentications is provided but not the other, the server may not provide an authentication either of the message or the transmission history of the message. 
     As will be appreciated, the history of the transmission of the message from the server through the intermediate stations to the recipient and then from the recipient through the same or different intermediate stations to the server is available when the authentication is provided to the sender, as disclosed and claimed in U.S. Pat. No. 7,966,372. Sometimes, however, the recipient may desire a prompt authentication of the transmission of the message and the transmission history. 
     As will be appreciated, the transmission history available to provide such an authentication is relatively brief Available information for the transmission history at the time of the message transmission to the recipient may constitute essentially only the identity of the sender, the identity of the server, the identity and internet address of the recipient and the time for the transmission of the message from the server to the recipient. 
       FIG. 12  schematically shows a system for authenticating a message to a recipient, and the transmission history of the message, from the server to the recipient. The system shown in  FIG. 12  is directed to the transmission of a court order from a court to an attorney for one of the parties in a lawsuit. When the attorney receives the message electronically as through the internet, the attorney may attempt to authenticate promptly the court order and the transmission of the court order. This may be particularly important to the attorney since the court order may direct the attorney to file a specified document within 24 hours or 48 hours in the court. 
     It will be appreciated that the example shown in  FIG. 12  is only one of a countless number of different examples that can be provided. For example, it may relate to all types of contractual matters where a first party in a proposed contractual relationship with a second party may be proposing particular contractual terms to a second party and may be requesting a prompt acceptance or rejection of these terms. Under such circumstances, the second party may request prompt confirmation of the terms that the second party has received and may request prompt confirmation that the first party has submitted these terms to the second party. 
     As indicated previously,  FIG. 12  shows on a schematic basis a system and a flow chart, generally indicated at  1200 , in which a court  1202  issues an order or a ruling to an attorney in a lawsuit in which the attorney is representing one of the parties in the suit. As a first step indicated at  1202 , the court  1202  issues the order, preferably electronically (e.g. via the internet) using, for example, the RPOST (R)egistered E-Mail® service. Messages transmitted and received by such registered e-mail are disclosed and claimed in U.S. Pat. No. 7,966,372, filed by Dr. Terrance A. Tomkow for a SYSTEM FOR, AND METHOD OF, AUTHENTICATING DELIVERY AND INTEGRITY OF ELECTRONIC MESSAGES on Jul. 27, 2000 and assigned of record to the assignee of record of this application. 
     As a first step in the method  1200  shown in  FIG. 12 , a U.S. court  1202  transmits a notification (e.g. a court order) in a lawsuit to a server  1204 . The transmission from the U.S. court to the server  1204  is indicated at  1206 . The notification may be by e-mail in accordance with the system and method claimed in U.S. Pat. No. 7,966,372. The server  1204  then transmits the notification to an attorney  1208  who represents one of the parties in the lawsuit. This transmission is indicated at  1210 . It may be by e-mail. The server  1204  also transmits a delivery receipt to the U.S. court to indicate that the notification has been delivered (or not delivered) to the attorney  1208  and the time of the delivery. This delivery receipt is indicated at  1212  in  FIG. 12 . The delivery  1212  may be a registered receipt. The U.S. court retains a copy of this notification to indicate the court order transmitted to the attorney  1208  and the time of the transmission and to indicate whether or not the notification has been received by the attorney  1208  and also whether or not the notification has been opened by the attorney&#39;s client. 
     The attorney  1208  can verify the authenticity of the notification by forwarding it to the server  1204 . See  1214 . The forwarding can be to a special website at the server  1204  such as “verifyatrpost.net”. By forwarding the notification to verifyatrpost.net, the attorney  1208  will receive an authentication receipt which will authenticate the notification and the time of transmission of the notification to the attorney  1208 . 
     The attorney  1208  can also forward the notification to any third party. The third party can then request authentication of the notification in the same manner as discussed in the previous paragraph with respect to authentication of the notification to the attorney  1208 . In this way, the authentication capability is retained by the attorney and is transferred to other parties even when the attorney  1208  forwards the notification to the third party. 
     The sophistication of the authentication capability can be enhanced by the server  1204  from that discussed above. The server can create a digital signature of the court order. The attorney  1208  can then transmit the message to the website verifyatrpost.net. The website can then produce a digital fingerprint (or digital digest) of the order transmitted by the attorney  1288  to the server  1204  and a digital fingerprint from the digital signature of the order from the court  1202 . When the two (2) digital fingerprints match, the server  1204  can authenticate the message. 
     When the server  1204  transmits the notification to the attorney  1208 , the server knows certain information such as the identity of the U.S. court, the identity and address of the recipient and the time of the transmission of the message to the recipient. This certain information may also include the identity of the server. The court order and the certain information specified in this paragraph may be transmitted to the attorney  1208 . To obtain an authentication of this information, the attorney  1208  forwards this information to the website verifyatrpost.net. In addition to the authentication discussed in the previous paragraph, the server  1204  can then verify the certain information such as the identity of the sender, the identity of the server, the identity and address of the recipient and the time of the transmission of the notification from the server to the recipient. This certain information can be compared with corresponding information at the server  1204  to provide an authentication at the server  1204  in addition to the authentication of the court order. 
     Instead of providing a digital signature of only the notification (court order), the server  1204  can also produce a digital signature of the notification and the certain information such as the identity of the sender, the identity of the server and the identity and address of attorney  1208 . The server  1204  can then transmit the notification and the certain information to the attorney  1208 . When the attorney  1208  desires to obtain an authentication, the attorney forwards the notification and the certain information to the website verifyatrpost.net at the server  1204 . The server  1204  then produces a digital fingerprint from the notification and the certain information from the attorney  1208  to the server  1204  and a digital fingerprint from the digital signature produced by the server  1204 . When the two (2) digital fingerprints match, the server  1204  is able to provide an authentication to the attorney  1208 . 
     In addition to providing a digital signature of the notification, the server  1204  may also provide a digital signature of the certain information such as the identity of the sender, the identity and address of each of the server  1204  and the attorney  1208  and the time of the transmission from the server to the attorney. The server  1204  may then transmit to the attorney  1208  the notification, the digital signature of the notification and the certain information. To obtain an authentication, the attorney  1208  forwards to the server  1204  at verifyatrpost.net the notification and the certain information. The server  1204  then produces digital fingerprints of the notification with the certain information and digital fingerprint(s) of the digital signature(s). The server compares the digital fingerprints of the notification and the digital fingerprint of the notification and compares the digital fingerprints of the certain information. When each of the comparisons matches, the server  1204  provides an authentication to the attorney  1208 . 
     The server  1204  also transmits to the court  1202  the notification, the digital signature of the notification and the transmission history between the servers  1204  and the attorney  1208 . As previously indicated, the transmission history may include the intermediate stations between the server  1204  and the attorney  1208  and may also include the times of transmission to the intermediate stations. If the server  1204  provides a digital signature of this transmission, the server  1204  may also transmit this digital signature to the court  1202 . When the attorney  1208  wishes to authenticate the message and the time of transmission of the message from the server  1204  to the attorney  1208 , the court  1202  may transmit to the server what the court has previously received from the server. The server  1204  may then use this information, in the manner described above, to authenticate to the attorney  1208  the notification and the time of transmission of the notification from the server to the attorney  1208 . 
     Another method of authenticating to a recipient also may consist of the following steps performed at the sender&#39;s mail client or mail transport agent. 
     1. A digital digest is taken of each attachment of the message. 
     2. A copy of the message is made, stripped of any file attachments and compressed or hashed. 
     3. The digital digests and the compressed body of the message are combined with information identifying the sender and are encrypted as an alphanumeric string. 
     4. A digital digest of this string is taken. 
     5. A file is prepared which contains, in HTML format, information identifying the sender and instructions on how to validate the message. The instructions invite anyone who wishes to confirm the integrity of the message to forward a copy of the message, with all its attachments in place, to an email address. The encrypted string is concealed within the file in an HTML comment field. Because the file does not contain copies of the original message&#39;s attachments, it may be quite small even though the message is large. 
     6. The HTML file is attached to the message and the message is sent. 
     On receiving this message, any recipient wishing to confirm the authenticity of the message can do so by forwarding it to the indicated address. When the forwarded message is delivered to the address, the sender of the original message or an agent of the sender can perform the following steps. 
     1. The encrypted string is extracted from the HTML attachment and decrypted. 
     2. Digital digests of the other file attachments of the message are computed and compared to the digital digests extracted from the encrypted string. 
     3. If the file digests are equivalent, indicating that the file attachments have not been changed, the body of the original message is extracted from the HTML file. Its digital digest is compared with the digest stored in the HTML file. If the digests are equivalent the compressed message body is decompressed and saved to a new file. 
     4. The file attachments of the submitted message are detached and attached to the new file. The new file is now a highly accurate reconstruction of the original message. 
     5. The reconstructed message is now attached to a message that identifies the original sender of the message and reports that a reconstruction of the original message is attached. This authenticating message is returned to the reply-address of the forwarded message. 
     If the digital digests indicate that either the file attachments, or the compressed string, have been altered, a message reporting a failure of authentication is returned to the reply-address of the forwarded message. 
     The system of “digitally sealing” a message is universal, non-fragile and resilient. It is universal insofar as any recipient of the message will be able to authenticate the message simply by forwarding it to the authentication address. 
     The system is not fragile since: so long as the message&#39;s file attachments are not corrupted, the message may be changed in many ways without interfering with its accurate reconstruction. 
     The system is resilient in the sense that an accurate copy of the original message can be reconstructed despite significant corruption of the message. 
       FIGS. 13 and 14  illustrate an embodiment of the system where the digital sealing operations are performed at a Mail Transport Agent removed from the sender. One such process for providing a digital seal is the DIGITAL SEAL service provided by RPOST. 
       FIG. 13  illustrates the sealing of a message by the server  1204 : 
     When the message is delivered to the server  1204  via an authenticated SMTP connection  1301 , the system consults a database  1302  to recover identifying information about the sender. This information is stored in a string or data element  1303 . 
     The file attachments of the message may be hashed as at  1304  and attached to the string  1303  to form a part of the string. 
     A copy is made of the original message as at  1305  and the message copy is stripped of its file attachments as at  1306 . 
     The result  1307  is appended to the string  1303  as a part of the string. String  1303  is hashed and the result  1307   a  is appended to the string  1303 . 
     The string  1303  is digitally compressed or hashed as at  1308  and encrypted as at  1309  and then attached to an HTML file  1310 , concealed in a comment. The comment is indicated in the file  1310 . Identifying information about the sender is included in plain text in the file  1310  as well as instructions about how to authenticate the message. These instructions include the identity of the sender and the particular web at the server  1204  to which the message, the attachments and the encrypted hash of the string are to be sent. 
     The HTML file is then attached as at  1311  to the original message and results are sent to the message&#39;s addressee (the recipient) as at  1312 . 
       FIG. 14  illustrates the process of authenticating a digitally sealed message such as indicated at  1312  in  FIG. 13 . 
     To authenticate the message the recipient forwards a copy to the server  1204  as at  1313 . The attachments and the encrypted hash of the string  1303  are included in the forwarding to the server  1204 . This is indicated at  1315   a.    
     The digitally sealed file is detached from the message file  1310  as at  1314  and the encrypted hashed string  1315  is extracted, decrypted as at  1316  and decompressed as at  1317 . 
     A hash of the string  1303 , less its encrypted hash, is taken as at  1318 . The result is compared as at  1319  to the hash of the string  1303 . If they are not equivalent the system sends a message to the submitter saying that the message cannot be authenticated because it has become corrupted. (See  1320 .) 
     If the hashes are the same ( 1321 ) the system hashes the file attachments  1322  of the original message and compares these as at  1323  to the hashes stored in  1323   a . If these are not equivalent the system returns a failure notification  1320 . 
     If the files are equivalent the system creates a new email message as at  1324  from the original message text (less file attachments) stored in  1315 . The file attachments of the submitted message are attached (see  1325 ) to the message  1324 . The message  1324  is now an accurate reconstruction of the original message. The reconstructed message  1324  is now attached as at  1326  to a message which reports successful authentication of submitted message  1327  and the result is sent to the addressee or recipient.  FIG. 15  indicates at  1500  that the sender composes a message and provides for the transmission by the sender, or by a server associated with the sender, by an e-mail  1502 , to a recipient. The sender is illustratively designated in the e-mail as bill@microsoft.com and the recipient is illustratively designated in the e-mail as larry@oracle.com. 
     The sender may operate a member  1504  such as a button to provide for the transmission of the message to the recipient as a registered e-mail  1506  using, e.g. RPOST&#39;s REGISTERED E-MAIL SERVICE. When the sender operates the button  1504  the sender has the right to select individual ones of a number of different service options (see  1512 ) indicated on a Send Menu  1516  which pops up when the sender indicates that the transmission of the message is to be by registered e-mail. 
     These service options include 
     Send Registered  1518   
     Send Registered Unmarked  1520   
     Send for Official Use Only  1522   
     Use the Reply Registered feature  1524   
     Use the DIGITAL SEAL feature  1526   
     Send encrypted (with OUTLOOK security integration) 
     Send Digitally Signed (with OUTLOOK security integration)  1528 . The sender then selects the desired service option on the Send Menu  1516 . 
     A REGISTERED E-MAIL tag is added to the subject line or marked at  1530 . The Address is then processed with checks sum and REGISTERED E-MAIL Domain (see  1532 ). When the recipient address is larry.smith@microsoft.com, the processed address may be larry.smith.&lt;checksum&gt;.microsoft.com@rpost.org where rpost.org indicates the identity of the website at the server. As indicated at  1534 , the sender&#39;s server routes the message to the registered e-mail server. 
     The system shown in  FIG. 16  corresponds to the system shown in  FIG. 15  except for the following changes: 
     1. A REGISTERED E-MAIL  1616  includes a box  1640  which is designated as “Digitally Sign”. This box is checked when it is desired to provide a digital signature of the message. 
     2. The registered e-mail  1616  includes a box  1642  which is designated as “Encrypt”. This box is checked when it is desired to provide an encryption. 
     3. Step  4  ( 1644 ) is designated “User Select.” For Official Use Only and Digitally Sign and Encrypt.” This specifically refers to the “Digitally Sign” Box  1640  and the Encryption Box  1642 . 
     4. Step  5  ( 1646 ) has the following designation: “The RPOST add-in attaches the encrypted/signed message to a new Registered “wrapping” message that contains the specified FOUO banner.” “FOUO” is a shortening of “for Official Use Only.” (See step  4  in  FIG. 16 .) 
     5.  FIG. 16  shows two (2) envelopes  1650  and  1652 . Envelope  1650  is designated as “Attached Encrypted Message” and Envelope  1652  is designated as “Registered Message”. 
     6.  FIG. 16  is designated as “For Official Use Only e-mail with Digital Signature and Encryption Diagram. 
     Overview 
     Note: 
       FIGS. 15 and 16  are block diagrams of a system for use with the embodiments shown in  FIGS. 12-14  in providing a transmission of a Registered e-mail message when a user presses a “button.” 
     RPost Digital Sealing 
     The OUTLOOK Registered e-Mail Button is a plug-in for MICROSOFT OUTLOOK 2000/XP. The purpose of the button is to provide the e-mail user with the ability to send REGISTERED E-MAIL from the OUTLOOK MUA. When the user has composed a message and is ready to send it, the installed plug-in gives the option to send the message as a standard non-registered message or as a “Registered” message. If the user elects to send a REGISTERED E-MAIL, a Send Menu pops-up that provides the sender with the following service options: 
     Send Registered 
     Send Registered Unmarked 
     Send For Official Use Only 
     Use the Reply Registered feature 
     Use the DIGITAL SEAL feature 
     Send Encrypted (with OUTLOOK security integration) 
     Send Digitally Signed (with OUTLOOK security integration) The only visible change to the OUTLOOK e-mail program is the addition of a “Send Registered” button in the tool bar of the message composition window and a Receipt folder that can be automatically added as a subdirectory to the in-box. All Registered Receipts are directed to this Receipt folder by default. 
     Process Overview 
     User Process 
     1. User composes message and adds any attachments. 
     2. User selects Send Registered (Either a button with the MICROSOFT OUTLOOK e-mail editor or a pop-up window with the MICROSOFT WORD e-mail editor). 
     3. A REGISTERED E-MAIL “Send Menu” GUI box appears offering the user service options. 
     4. The user selects the desired option(s). 
     a. A special REGISTERED E-MAIL domain is added. 
     b. A security checksum is added. An example of a processed address follows: 
     Recipient Address: larry.smith@microsoft.com 
     Processed Address: larry.smith.&lt;Checksum&gt;.microsoft.com@rpost.org 
       FIGS. 15 and 16  are block diagrams of a system for use with the embodiment shown in  FIGS. 12-14  in providing a transmission of an encrypted digitally sealed e-mail message when a user presses “button  1504 ” and indicates that the user desires the message to be encrypted and digitally sealed. 
     The RPOST DIGITAL SEAL provides the recipient, or any future recipient, the ability to ensure the integrity and verify the e-mail origin. It protects the sender against misrepresentation or hoaxes. What makes this service particularly unique, versus PKI digitally signed e-mail, is that the DIGITAL SEAL is durable, works on all e-mail systems, and can be signed by the author. Specifically, (1) any future recipient (second, third+) can verify origin and integrity; (2) any recipient can regenerate the original e-mail and original attachments; (3) any recipient can verify author&#39;s signature and original content; and (4) it works for all e-mail systems (including Webmail). RPOST does not store e-mail or portions of e-mail. 
     When the DIGITAL SEAL option is selected, the RPOST “OUTLOOK Add-in” software processes the message so that the identity of the sender and the integrity of the message contents can be established and verified by the Registered e-Mail processing system. This is done using industry standard, cryptographic algorithms, which are implemented using the MICROSOFT CAPICOM v.2.0 Library. RPOST encryption uses MICROSOFT CrytoAPI 2.0 NIST FIPS-141-1 validated instances of the SHA-1 and 3DES (triple DES) algorithms. The processes is described below. 
     Outlook Add-in Digital Seal Processing 
     Note: This is an example featuring the Registered service with digital sealing. 
     1. User composes message and adds any attachments. 
     2. User selects option to send the message Registered and Digitally Sealed. 
     3. User enters user&#39;s “Signature Password” for user&#39;s RPOST DIGITAL SEAL. 
     4. Message is processed for digital sealing: 
     a. Password is used as salt for SHA-1 (Secure Hashing Algorithm) hash of message and attachments. 
     b. SHA-1 hash of password is produced. 
     5. Message is re-addressed for REGISTERED E-MAIL system delivery (including authentication checksum). 
     6. Message is delivered to local mail server for delivery including: 
     a. SHA-1 message digest (password salted) 
     b. SHA-1 hash of message attachments (password salted) 
     c. SHA-1 hash of password Once the message arrives at the Registered e-mail processing system, a verification process is used to check authenticity and integrity. A key element of the verification process is the REGISTERED E-MAIL User DIGITAL SEAL Password Store. This stores passwords for all enabled users of RPOST Digital Sealing. 
     Registered E-Mail System Server Side Digital Seal Processing 
     REGISTERED E-MAIL systems receives the message including: 
     1. SHA-1 message digest (password salted). 
     2. SHA-1 hash of message attachments (password salted). 
     3. SHA-1 hash of password. 
     4. The password hash is compared to the appropriate password hash obtained from the REGISTERED E-MAIL User DIGITAL SEAL Password Store for verification of user identity. 
     5. The message and attachments are processed with the SHA-1 hash algorithm (using password salt). 
     6. The resulting hashes are compared with the appropriate hash values included with the message for integrity verification. 
     7. Following this verification process the REGISTERED E-MAIL servers prepare the message to be sent to the recipient(s) digitally sealed. 
     Encrypted/Digitally Signed E-Mail 
     The e-mail security features within OUTLOOK can be used in conjunction with the REGISTERED E-MAIL service so that users can utilize Public Key Infrastructure cryptography with messages that are also Registered with RPOST technology. 
     MICROSOFT OUTLOOK integrates with the WINDOWS certificate stores to provide the options to send messages encrypted and/or digitally signed. To do this, the user must have a Digital Certificate in the Certification store that is \issued and signed by a Certificate Authority. 
     The configuration panel for REGISTERED E-MAIL in the OUTLOOK tools-options area allows the user to select OUTLOOK Encryption Integration. A user can select a secure e-mail Digital Certificate from their WINDOWS Certificate store to use with this process. This results in the addition of the following two options to the “Send Registered” Send Menu in the sending process: 
     Encrypt 
     Digitally Sign These options utilize the user&#39;s configured Digital ID to encrypt and/or digitally sign the REGISTERED E-MAIL. 
     If a user elects to encrypt and/or sign a message, the resulting ciphertext and digital ID are encapsulated as message attachments during the processing of the message by the RPOST add-in software. If a user selects the options to encrypt and digitally sign e-mail in the OUTLOOK editor, this will also have the same result. The MICROSOFT COM interfaces allow the COM add-in to detect the presence of the encrypt and digitally sign options when the “Send Registered” button is selected. If the encrypt or digitally sign options are selected as well, then the RPOST system performs the required encapsulation. 
     Note: 
     If MICROSOFT WORD is used as the e-mail editor the OUTLOOK encryption/digital signature option must not be used. The option provided by the REGISTERED E-MAIL options must be used for encrypted/digitally signed e-mail. 
     Note: 
     Digitally signing a message allows the first recipient to verify the integrity and authenticity of the message based on the CA trust model in PKI. Encrypting a message ensures the confidentiality of the message. The encrypted message can only be decrypted by someone with access to the corresponding private key (ideally the intended recipient). 
     The REGISTERED E-MAIL system cannot decrypt messages that are encrypted using the Public Key Infrastructure. This is not required to verify the authenticity, integrity and delivery status of the message. However, the encapsulated ciphertext will be delivered to the intended recipient for decryption. 
     Technical Implementation Notes 
     Com Add-in Technology 
     The REGISTERED E-MAIL button has been developed using COM Add-in technology. MICROSOFT introduced this technology called COM add-ins for OFFICE 2000 and above to make extending MICROSOFT OFFICE easier for developers. These add-ins can be built using any COM compliant tool including VBA, VISUAL Basic and VISUAL C++. 
     The architecture for COM add-ins is straightforward. On the one hand, you have an Office application, in this case OUTLOOK, that serves as a host for the add-in. On the other hand, you have the add-in that has been developed, which is an in-process COM server. Essentially, a COM add-in is a compiled DLL that is written and registered so that OFFICE knows how to load and communicate with the add-in. By writing the add-in as a DLL, you get the speed of running the code in-process with the host application. This provides tremendous performance benefits. 
     Cryptographic Standards &amp; Implementation 
     The hash algorithm used in this software is SHA-1 (Secure Hash Algorithm). This was developed by NIST and NSA and produces a 160-bit hash value. SHA is a standard algorithm used in government communications. 
     The cryptography techniques used in this software are implemented using the MICROSOFT CAPICOM (version 2.0) libraries. The CAPICOM COM client provides services that enable application developers to add security based on cryptography to applications. CrytoAPI includes functionality for authentication using digital signatures, for enveloping messages and for encrypting and decrypting data. RPOST encryption uses MICROSOFT CrytoAPI 2.0 NIST FIPS-141-1 validated instances of the SHA-1 and 3DES (triple DES) algorithms. 
     Although the present invention has been described in detail with regard to the preferred embodiments and drawings thereof, it should be apparent to those of ordinary skill in the art that various adaptations and modifications of the present invention may be accomplished without departing from the spirit and the scope of the invention. Accordingly, it is to be understood that the detailed description and the accompanying drawings as set forth hereinabove are not intended to limit the breadth of the present invention.