Patent Publication Number: US-6701347-B1

Title: Method for including a self-removing code in a self-removing email message that contains an advertisement

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of commonly owned copending application Ser. No. 09/399,066 filed Sep. 18, 1999, through which this application also claims priority to application Ser. No. 60/101,517 filed Sep. 23, 1998 and to application Ser. No. 60/104,138 filed Oct. 14, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the technical goal of facilitating the use of email (electronic mail) and similar broadcast or targeted transmission mechanisms by automatically deleting information copies after their receipt. 
     TECHNICAL BACKGROUND OF THE INVENTION 
     Email is a very useful tool for promoting communication between people who are separated by distance, by different working hours, or both. However, email is sometimes inconvenient for recipients. This hinders the use of email as a mechanism for broadcasting information to many people and/or transmitting information to one or a few specific targets. 
     Email creates annoyances which have not been fully addressed. One common source of annoyance is “spam ” email, namely, unsolicited email sent to multiple recipients. Unlike passive advertising, such as pop-up and banner ads on websites, and ads in more traditional print, radio, or television media, “spam ” email seeks out its audience, and thrusts itself into the viewer&#39;s field of attention without being invited. This can be very annoying because it interrupts other activities, consumes system resources, and perhaps most importantly, requires active efforts by recipients who want to dispose of these unwanted messages. An email recipient may delete unwanted messages manually by using an email Delete command in an email client (e.g., a desktop application program, or web mail pages in a web browser), by dragging the messages in question to a trash can, or by similar steps. 
     Some email systems provide filters that detect at least some incoming unsolicited email and either deletes it or, more typically, places it in a directory or folder reserved for such messages. But filters sometimes err, either by characterizing as unsolicited email a message that is not, or by failing to detect unsolicited email and letting it through with the normal correspondence from familiar senders. Thus, it would be helpful to provide some alternate or additional means for disposing of unsolicited email. 
     Some unsolicited email includes a statement that sending a reply with “REMOVE ” in the subject field will remove the recipient from the mailing list. It has been alleged, however, that any reply to some such unsolicited email will simply confirm that the address to which the unsolicited mail was sent is “good ” (meaning someone actually looked at the unsolicited email) and that a reply asking to be removed from the mailing list may therefore have an effect opposite from the intended effect. If this is so, then only addresses from which no reply is received would have a chance of being removed from the list. 
     Moreover, even some mail which is unsolicited is of interest to the recipient only for a limited time. For instance, the fact that a recipient has voluntarily subscribed to an electronic newsletter, a news service, or a listserv list does not necessarily mean that the recipient wants to keep every message from that subscription after reading it. Indeed, despite having subscribed to the service, the recipient may not even want to read each and every message from the subscription service. 
     Television and radio “spots ” which broadcast an advertisement without taking up storage space on the receiver (televisions and radios generally lack permanent storage such as hard disks) are known, although this characterization of them as not requiring recipient storage resources and proactive deletion by the recipient may be new. 
     Accordingly, it would be an advancement to provide an improved approach to email and similar messaging which moves the email message disposal burden off the shoulders of the recipient. In particular and without limitation, it would be an advance to make public notices and news sent through email less onerous to recipients, and likewise to make email advertisements (including without limitation coupons, contact information, descriptions of goods and/or services, comparisons, and promotional materials) available to multiple recipients without requiring that recipients affirmatively remove unwanted advertisements from their computer systems or create a reply message having REMOVE or another keyword in the subject, to indicate their lack of interest in the subject matter being advertised. 
     Such approaches for improved email messaging are disclosed and claimed herein. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to methods, articles, signals, and systems for self-removing email messages. Self-removal of email (or other transmitted digital information presentations) can provide at least two advantages. First, self-removing email can be used to enhance the security of a system by reducing the number of message copies and the life span of those copies. Second, self-removing email can be used to reduce the inconvenience of unsolicited email by making it possible for officials, advertisers, and other broadcast email originators to present messages that do not have to be manually removed by the target audience. A given method, article, signal, or system may use self-removing email to enhance message security, to reduce recipient annoyance, or both. 
     In some embodiments, self-removing email messages are encrypted with conventional tools and techniques. To further enhance security, a message is closely coupled to executable code which reduces the number of copies of the message. Some versions of the code allow any given copy of the message to be viewed at most once. 
     In some embodiments, self-removing email messages contain advertisements, but the invention may also be used to broadcast or otherwise transmit self-removing email messages which contain other materials that, at least by default, are not stored long-term on the recipient&#39;s hard disk or on other intervening nodes (the self-removal action may sometimes be expressly overridden). For instance, news items, confidential materials, and other materials directed to a limited audience such as public notices (changes in the law, election results, tax auction notices, public hearing announcements, and so on), private club notices, and materials intended for mature audiences, may also be transmitted in self-removing email messages. 
     Unlike traditional email, self-removing email places the burden of selecting messages for removal and then removing them on the software and on the message originator, instead of on the message recipient. “Spam ” advertising methods become much less onerous to recipients if the email carrying the advertisements is as effortlessly ephemeral (from the recipient&#39;s point of view) as a television or radio commercial. Other aspects and advantages of the present invention will become more fully apparent through the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     To illustrate the manner in which the advantages and features of the invention are obtained, a more particular description of the invention will be given with reference to the attached drawings. These drawings only illustrate selected aspects of the invention and thus do not limit the invention&#39;s scope. In the drawings: 
     FIG. 1 is a diagram illustrating computers and computer networks suitable for use according to the invention by means of configuration with special-purpose hardware and/or software described herein. 
     FIG. 2 is a data flow diagram illustrating a method, signal, and environment using self-removing messages to carry messages from an originator through a network to one or more recipients. 
     FIG. 3 is a data flow diagram further illustrating embodiments of the invention used to increase recipient convenience, and also further illustrating removal indicators and removal code shown in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In describing methods, devices, and systems according to the invention, the meaning of several important terms is clarified, so the claims must be read with careful attention to these clarifications. Specific examples are given to illustrate aspects of the invention, but those of skill in the relevant art(s) will understand that other examples may also fall within the meaning of the terms used, and hence within the scope of one or more claims. Important terms are defined, either explicitly or implicitly, both here in the Detailed Description and elsewhere in the application file. 
     Computers, Networks 
     The invention may be used to protect and/or ultimately remove email messages from an individual computer or from one or more computers in a network, including copies of messages stored on removable media or transmitted over a network link and stored on intermediate nodes. FIG. 1 illustrates a system  100  having several computers and several networks  102 ,  104 ,  116  which can be configured according to the invention, but those of skill in the art will understand that suitable computer networks include various networks, such as local area networks, wide area networks, metropolitan area networks, and/or various “Internet ” or IP networks such as the WorldWide Web, a private Internet, a secure Internet, a value-added network, a virtual private network, an extranet, or an intranet. 
     The system  100  shown as an example in FIG. 1 includes two local area networks  102 ,  104 . Each network  102 ,  104  includes at least one computer  106 , and each computer  106  includes at least a processor and a memory; computers  106  also include various input devices and/or output devices. The processor may include a general purpose device such as a 80×86, Pentium (mark of Intel), 680×0, or other “off-the-shelf” microprocessor. The processor may include a special purpose processing device such as an ASIC, PAL, PLA, PLD, or other customized or programmable device. The memory may include static RAM, dynamic RAM, flash memory, ROM, CD-ROM, disk, tape, magnetic, optical, or another computer storage medium. The input device(s) may include a keyboard, mouse, touch screen, light pen, tablet, microphone, position sensor, pressure sensor, thermal sensor, or other input hardware with accompanying firmware and/or software. The output device(s) may include a monitor or other display, printer, speech or text synthesizer, solenoid, switch, signal line, or other process controller. 
     The network  102 , which is also by itself one of the many networks suitable for use with the invention, includes a server  108  and several clients  110 . Other suitable networks may contain other combinations of servers, clients, and/or peer-to-peer nodes, and a given computer may function both as a client and as a server. For instance, network  104  is a peer-to-peer network. The computers  106  connected by a suitable network may be work-stations, laptop computers  112 , disconnectable mobile computers, servers, mainframes, clusters, network computers or lean clients, personal digital assistants or hand-held computing devices  114 , or a combination thereof. 
     A local network such as network  102  or network  104  may include communications or networking software such as the software available from Novell, Microsoft, Artisoft, and other vendors. A larger network such as the network  100 , may combine smaller network(s) and/or devices such as routers and bridges  116 . Large or small, the networks may operate using TCP/IP, SPX, IPX, and other protocols over twisted pair, coaxial, or optical fiber cables, telephone lines, satellites, microwave relays, modulated AC power lines, physical media transfer, and/or other data carrying transmission “wires”  118  known to those of skill in the art; for convenience “wires ” includes infrared, radio frequency, and other wireless links or connections. Like the network  100 , a suitable network may encompass smaller networks. Alternatively, or in addition, a suitable network may be connectable to other networks through a gateway or similar mechanism. 
     At least one of the computers  106  is capable of using a floppy drive, tape drive, optical drive, magneto-optical drive, or other means to read a storage medium  120 . A suitable storage medium  120  includes a magnetic, optical, or other computer-readable storage device having a specific physical configuration. Suitable storage devices include floppy disks, hard disks, tape, CD-ROMs, PROMs, random access memory, flash memory, and other computer system storage devices. The physical configuration represents data and instructions which cause the computer system to operate in a specific and predefined manner as described herein. Thus, the medium  120  tangibly embodies a program, functions, and/or instructions that are executable by computer(s) to protect and/or delete email message contents substantially as described herein. 
     Suitable software languages and tools to assist in implementing the various devices, signals, systems, and methods of the invention are readily employed by those of skill in the pertinent art(s) using the teachings presented here and programming languages and tools such as Java, Pascal, C++, C, Perl, database languages, APIs, various system level SDKs, assembly, firmware, microcode, and/or other languages and tools. 
     Personal Messaging with Self-removing Messages 
     FIG. 2 illustrates a method and environment using self-removing messages to carry messages from an originator  200  at some origin to one or a few recipients  202 . As used here, “a few ” means less than ten recipients, or alternatively, a small number of recipients who are personally known to the originator; news items, notices, advertisements and/or other messages directed to more than a few recipients are discussed elsewhere herein, although many of the tools and techniques taught herein apply regardless of whether there are only a few recipients. 
     During a creating step  204  the originator  200  creates a self-removing message  206  using software and hardware configured by the software, or using custom hardware alone, according to the teachings herein. This may be done generally in accordance with familiar tools and techniques for email messaging, attaching files, embedding graphics, encrypting data, and/or compressing data, but it must associate code and/or hardware  208 , and/or indicators  210 , with the message  206  to perform or facilitate the self-removal message management functions described here. That is, the originator  200  (or equivalently, an embodiment under the originator&#39;s direction) marks the message  206  at the origin, includes removal code  208  in the message  206 , or does both. The code  208  may be embedded solely in the message  206 , but it may also be embedded in plug-ins, modules, routines, objects, threads, or other forms in an ISP&#39;s transmission program  224  and/or a recipient&#39;s browser or email reception program  226 , or the code  208  may be divided between one or more such locations. Code and/or hardware  208 , and indicators  210 , are collectively termed “self-removal enhancements ” herein. 
     In addition to the message self-removal code  208  in the message  206  and/or elsewhere, the message  206  often includes one or more self-removal indicators  210  such as bitflags, header values, file name extensions, or other data marking the message  206 , thereby identifying the entire message  206  or a portion thereof to the removal code  208  and distinguishing the message  206  from messages which are not subject to removal by the means taught herein. Of course, in a system where all messages are entirely self-removing, the indicators  210  are optional unless they are needed to detail information such as how long to display the message contents to the recipient, whether to allow recipients to scroll back through a previously displayed portion of the message contents, and so on. However, batch files, message handling rules, and other deletion controls that are provided by the recipient  202  are not indicators  210 , since they do not give originators  200  and/or distributors  222  the responsibility for, and the initial control over, removal of messages at the recipient&#39;s location. 
     In embodiments preferred for this present application, the originator  200  or an embodiment under the originator&#39;s direction marks the message  206  at the origin with one or more indicators  210  to facilitate the self-removal message management functions described here. In these embodiments, removal code  208  is not included in the message  206 . Instead, removal code  208  is embedded in plug-ins, modules, routines, objects, threads, or other forms in a recipient&#39;s browser or email reception program  226 . However, the initial decision to make a given message be self-removing still rests with the originator  200  (or with an ISP  222 ), rather than making the recipient  202  actively delete the message. 
     In these presently preferred embodiments, self-removal indicators  210  in a given email message  206  permit the originator  200  and/or an intermediate node  220  to indicate to the removal code  208  one or more of the following options: 
     (a) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox shortly after being opened by that recipient, e.g., delete the message approximately five minutes after it is opened; 
     (b) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox no later than a specified time after being opened by that recipient, and may be deleted before that specified time, e.g., delete the message within 24 hours of receiving it; 
     (c) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox no sooner than a specified time after being opened by that recipient, and may be deleted any time after that specified time, e.g., give the recipient 24 hours to make copies, reply, forward the message or otherwise react to the message  206 , but delete it after that specified time has elapsed; 
     (d) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox no sooner than a first specified time after being opened by that recipient, and no later than a second specified time after being opened, e.g., delete the message within one to seven days of receiving it; 
     (e) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox no later than a specified time after being received, regardless of whether it has been opened by that recipient; 
     (f) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox no sooner than a specified time after being received, regardless of whether it has been opened by that recipient; 
     (g) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox between a first and second specified time after being received, regardless of whether it has been opened by that recipient; 
     (h) the message  206  is to be deleted automatically by the removal code  208  according to some combination of chronological and/or “has been opened ” criteria generally as discussed above, but the chronological criterion is a fixed time or date, rather than an elapsed time, e.g., delete the message  206  no later than Jul. 4, 2001 regardless of whether it has been opened by that date; 
     (i) the message  206  is to be deleted automatically by the removal code  208  according to some combination of chronological and/or “has been opened ” criteria generally as discussed above, but instead of deleting the message only if it has been opened, or deleting it regardless of whether it has been opened, delete the message only if it has not been opened, e.g., if the recipient doesn&#39;t bother to open the message  206  because the subject line indicates it is an unwanted solicitation, then the message will be deleted automatically approximately one week after it was received; 
     (j) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox, after it has been opened, when a specified storage limitation is reached, e.g., too many messages or too much storage used for messages; 
     (k) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox when a specified storage limitation is reached, regardless of whether it has been opened by that recipient; 
     (l) the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox when the next message is received from the same source, regardless of whether the first message from that source has been opened by that recipient, e.g., automatically keep for the recipient only the latest news item from a newsletter subscription; 
     Note that conventional options for handling attachments may be combined with the removal indicators  210 . For instance, conventional email clients such as the Eudora Pro 3.0 program permit one to specify whether an attachment to a message should be deleted when the message is manually deleted. In the present invention, a similar option can specify whether to keep attachments when a self-removing message  206  is automatically deleted. 
     Note that actions somewhat like these may be taken by a recipient, without any express removal indicator  210  in an email message. For instance, a recipient&#39;s email client  226  could be configured to automatically delete any message which remains unopened for more than one week. Likewise, a recipient&#39;s email client  226  could be configured to make automatic deletion of a message be the default disposition after the message has been opened. That is, the recipient must manually save desired messages, unlike the conventional approach in which recipients must manually delete undesired messages. 
     However, to clearly shift the burden of message removal from recipients  202  to originators  200  and/or distributors  222 , the message  206  includes one or more express removal indicators  210  which are placed there by the originators  200  and/or distributors  222  to make removal of the message  202  an automatic default result. The actual deletion is performed by the recipient&#39;s software  226 , but this is done in response to the instructions  210  from the originator  200  and/or distributor  222 . Thus, a message subject line such as “GET RICH ” or “HOT STOCK TIP ” is not a removal indicator  210 , even if the recipient has installed a filter that deletes messages containing that subject line, unless the message originator places the subject line in the message with the expectation that the recipient&#39;s email tool  226  will automatically delete the message in response to the subject line. Such subject lines are conventionally used to provoke an inquiry or another email reply, not to ensure that the message will be automatically deleted by the recipient&#39;s software. 
     In short, a removal indicator  210  provides an originator  200  and/or a distributor  222  with initial control over the deletion of a message after the message reaches the recipient  202 . The control is “initial ” in that, in some cases the recipient may override the instructions  210  of the originator  200  and/or distributor  222 , such as by saving message content  212  that would otherwise be automatically deleted. But the default handling of the message  206 , i.e., the handling in the absence of intervention by the recipient  202 , is specified by the originator  200  and/or a distributor  222  via the removal indicator(s)  210 . 
     The message  206  normally includes content  212  which is meant to convey information from the originator  200  to the recipient(s)  202 . The message content  212  may be in the form of text (e.g., word processor documents), images (e.g., still or motion image or video files), sounds (e.g., MP3, WAV, or other aural files), or other sensible items, and it may be in-line and/or provided as attachments. Word processors, conventional email tools, and other familiar tools and techniques may be used to select and/or create the message content  212 . 
     The message  206  optionally includes display code  214  and/or security code  216 , each of which is discussed further below. 
     Unlike previous email systems, chat rooms, and other conventional messaging systems, the present invention thus gives email message originators  200  and/or major service providers such as America Online both the opportunity and the presumed burden of marking for removal at least some of the messages  206  they originate or distribute. In conventional email systems, by contrast, recipients are burdened with removing essentially all unwanted messages. The invention promotes efficiency by having the originator  200  and/or distributor  222 , who know the message contents  212  and their intended effect, mark the messages  206  for removal after their arrival. This is better than making one or many recipients, who did not necessarily ask to receive the message, attend to its disposal. 
     The invention also gives originators  200  and/or distributors  222  a choice regarding the transience of their message content  212  at the recipient&#39;s location. In conventional chat rooms and instant messaging systems, by contrast, messages are ephemeral at the recipient&#39;s station regardless of whether the originator or distributor wishes them to persist there, because they often scroll off the visible display window or screen until they are beyond the recipient&#39;s reach. 
     During one or more transmitting steps  218  the message  206  is transmitted over the signal means  118  from the originator  200  to the recipient(s)  202 , possibly via a distributor  222 . This may be done generally in accordance with familiar tools and techniques for packet formation, storage, forwarding, error handling, and/or other network  100  transmission means. As the message  206  travels over one or more networks, transmission software and/or hardware in bridges and/or routers  116 , servers  108  (including without limitation ISP servers and application servers), and other network intermediate nodes  220  have access to part of all of the message. This access is facilitated by and/or subject to control by distributors  222 , namely, ISPs (and other access providers), other authorities, including governmental authorities, and other parties who are neither the message&#39;s originator nor the message&#39;s intended ultimate recipient. The nodes  220  operate at least in part using conventional networking tools and techniques  224 . After they have forwarded or otherwise processed in a conventional manner those portions, these novel intermediate nodes  220  can then delete, shred, or otherwise enhance the security of the message  206  portions by removing them as taught herein. 
     ISPs and other message distributors  222  may simply forward messages  206 . However, the nodes  220  may also be enhanced according to the present invention. For instance, message removal software and/or hardware  208  may configure the intermediate nodes  220  to provide novel capabilities which include identifying packets or other message  206  portions, up to and including the entire message  206 , through the self-removal indicators  210  and/or modifying messages  206 . 
     For instance, distributors  222  may verify that email messages  206  from a given originator  200  contain agreed-upon removal indicators  210 . In particular, for the convenience of advertising message recipients, a distributor  222  may grant use of a member list of email addresses for limited advertising purposes on condition that the emailed advertisements contain indicators  210  which will cause them to be automatically removed. The distributor  222  may then check some or all of the messages  206  to verify compliance with that contractual requirement. 
     Alternately, the agreed-upon removal indicators  210  may be actually inserted by the distributor  222 , pursuant to a contractual requirement or to distributor  222  operating policy. Identification of messages for indicator  210  insertion may be based on the originator&#39;s email address, on the subject line of the message, and/or on other filtering criteria. For instance, an access provider  222  may insert removal indicators  210  in all messages (regardless of origination address) which contain “$$$ ” in the subject line, so that those messages are automatically deleted one day after being opened or one week after being received, whichever occurs first. 
     For instance, an access provider  222  such as AOL, CompuServe, or Prodigy may permit controlled mailings to its members on condition that each message  206  include an indicator  210  that will cause the message  206  to be automatically removed from the recipient member&#39;s email “In Box ” after the recipient member  202  opens it, unless the recipient  202  actively overrides that removal to save the message&#39;s contents  212 . Likewise, an ISP could use indicators  210  to implement a promise that authorized email advertisements will consume no more than one half-megabyte of a recipient&#39;s hard drive, by having the indicators  210  set to cause automatic deletion of messages from a given list of sources, thereby freeing drive space, when the total space used by all messages from those sources exceeds a storage limit of one half-megabyte. Indicators  210  could likewise indicate that self-removing messages  206  should be removed when the hard drive or partition holding them has only a specified amount of free space left, or when a specified percentage of the total drive/partition space becomes used. 
     In some embodiments, the email tool  226  warns users that messages  206  are subject to automatic deletion. Accordingly, a message  206  which meets the automatic removal criteria (e.g., “$$$ ” in the subject line) can be preserved by the recipient  202  if they so desire, despite the insertion of removal indicators  210  by the access provider  222  and/or by the message originator  200 . 
     Eventually a transmission step  218  brings the message  206  to a recipient&#39;s station  226 . This may be done generally in accordance with familiar tools and techniques, including without limitation web browsers and email programs adapted with at least removal code  208  according to the invention through plug-ins or other means, and protocols such as SMTP, MIME, POP, IMAP, Privacy Enhanced Mail, listserv protocols, and usenet protocols. At the recipient&#39;s station  226  the message  206  is optionally authenticated  228 , optionally decrypted  230 , displayed  232 , removed  234  by removal code  208  operating in response to message indicators  210  in the message  206 , and optionally acknowledged  236 . Each of these steps is discussed at various points herein; at present, the focus is on the displaying step  232  and the removing step  234 . 
     During the displaying step  232 , the message content  212  is displayed  232  to the recipient  202 . This may be done immediately upon arrival of the message  206  without prompting from the recipient  202 , or it may occur as a result of the message&#39;s icon or title being highlighted, opened, clicked on, or otherwise activated by the recipient  202 . The displaying step  232  may limit message contents  212  to volatile memory (as opposed to disk or other non-volatile storage), may prevent forwarding of the message  206 , may disable screen save functionality, may overwrite the message contents  212  shortly after displaying them, may give the recipient  202  the option of overriding some or all of these default settings, and so on, as described herein. In particular, the recipient  202  may be warned that the message  206  is subject to automatic removal. 
     Finally, the message  206  is removed  234  by overwriting the window or screen that displayed it, by deleting it or otherwise moving it from an In Box to a Trash folder or the like, by marking the space it occupies as free, by erasing its contents from disk, and/or in other ways, as discussed herein. Messages  206  may also be removed after being only partly displayed, or after sufficient time passes or some other event occurs, such as a reboot, or an browser restart. 
     Broadcasting with Self-removing Messages 
     The novel tools and techniques illustrated in FIG. 2 can also be used when the originator  200  sends a self-removing message  206  to more than a few recipients  202 . For instance, public agencies and private litigants may wish to send messages  206  containing legal notices of the type which are conventionally published in newspapers. In the case of public agencies, email address databases could be compiled in connection with tax payments, corporate and professional license registrations and renewals, driver license registrations and renewals, and similar governmental functions. Care would be taken (and appropriate legislation and/or regulations put in place) to limit or prevent the use of such governmental email address databases by private or quasi-private entities. 
     However, private entities may appropriately use the invention, in accordance with applicable law, to broadcast self-removing messages  206  to large target audiences. For instance, a business might send registered customers new product announcements or press releases. Likewise, a private club or organization (or a business) might send event announcements to its members (or prospects) using self-removing messages  206 . Subscribers to newsletters or other news services may also receive news items in the content  212  of self-removing messages  206 . 
     Advertising and News with Self-removing Messages 
     One email broadcast use of particular interest to businesses is the use of email for advertising. Another broadcast use is email news, in the form of newsletters, article summaries with links to articles on web pages, and the like. Such advertising and news broadcasts may be mass market, or targeted demographic, or still more focused, as when a list of previous customer email addresses is used. However, conventional email advertising and news updates impose on the recipient at the same time, sometimes doing so even as they directly or indirectly solicit business from the recipient. Conventional approaches also consume storage on intermediate network nodes, thereby imposing on Internet Service Providers and similar entities (AOL, CompuServe, Prodigy, and so on). 
     By shifting the burden of message disposal away from recipients  202  and onto the system  100  and the originator  200 , the invention reduces the tension created by simultaneously imposing on the recipient to dispose of the message and asking the recipient to investigate or purchase the advertised products or services, or to visit the news provider&#39;s web site, which often carries advertising. Reducing this tension will make direct and indirect email advertising better received and hence more effective. 
     In one embodiment, self-removing email messages  206  contain advertisements of any of a broad range of services and goods which are presently described in unsolicited mass-mailing emails, in website banner ads, in television or radio spots, in newspapers and magazines, and in other forms and media. In one embodiment, they contain news items which are mailed to subscribers who voluntarily provided their email addresses for that purpose. Unlike television, radio, newspapers, and magazines, ads and news sent through the Internet and other electronic media can be relatively inexpensive, targeted, interactive, and/or provide hot links to web sites, newsgroups, IRC channels, and other digital network resources. Like unsolicited emails and banner ads, the messages  206  can be animated, with audio and/or visual components, and hot links. Unlike unsolicited emails and some banner ads, the self-removing message files  206  of the present invention do not require that recipients  202  affirmatively remove unwanted ads or old news from their computer system disk or create a reply message having REMOVE in the subject, to indicate their lack of interest in the subject matter being advertised, to conserve space, and/or to reduce clutter in their inbox. 
     Self-removing email tools and techniques described herein can also be used to broadcast, multicast, or otherwise transmit explicit (intended for mature audiences only) materials without requiring permanent storage of such materials on the recipient&#39;s computer system. Some people  200 ,  202  may find this useful for medical or health discussions, such as support groups and professionals dealing with the difficult personal and social issues arising from conditions such as breast cancer or acquired immune deficiency syndrome. Some people may also find this useful for personal entertainment using sexually explicit materials. Within the bounds allowed by law, the invention may assist such uses. 
     Examples Focused on Recipient Convenience 
     FIG. 3 illustrates a subset of the embodiments illustrated in FIGS. 1 and 2. Except as noted otherwise below, the illustrated steps and components are as described elsewhere herein. However, these embodiments focus on increasing convenience to the recipient through automatic removal of messages, rather than increasing security through such removal. Although security measures such as encryption, security code  216 , secure deletion in the form of electronic shredding, atomicity in display code  214 , incremental overwrites while incrementally displaying message content, Print Screen disabling, message self-modification, searches for additional message copies, and authentication may be employed in embodiments according to FIG. 3, they are not central to the invention in such embodiments. 
     FIG. 3 also further illustrates the removal indicators  210 , which may be used in embodiments according to any of the Figures. Four sample categories of indicators  210  are shown. A first category of indicators  300  includes indicators  210  which control automatic message  206  removal according to whether the message  206  has been opened by the recipient  202 . For instance, an indicator  300  may specify that the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox within one to seven days of when the recipient  202  opens the message  206  to read it. 
     A second category of indicators  302  includes indicators  210  which control automatic message  206  removal according to whether a fixed time and/or date has been reached, or a specified time has elapsed since some event such as original transmission of the message, receipt of the message, or first opening of the message. For instance, an indicator  302  may specify that the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox on Dec. 31, 2001. 
     A third category of indicators  304  includes indicators  210  which control automatic message  206  removal according to conditions involving a replacement message. A replacement message replaces a prior message, so the prior message is deleted. For instance, an indicator  304  may specify that the message  206  is to be deleted automatically by the removal code  208  from a recipient&#39;s mailbox/inbox after that recipient receives the next message from LawPlusPlus.com with “Update ” in the subject. Similarly, an indicator  304  may specify that a message  206  is to be deleted automatically by the removal code  208  from a recipient&#39;s mailbox/inbox if a replacement message is not received by the recipient  202  by a specified date or within a specified period after the first message  206  is received. 
     Earlier message(s) to be replaced may be identified in the replacement message by one or more values such as source address, date, or subject line. Messages being replaced are preferably also identified by a key, certificate, password, or other authentication mechanism presented by the replacement message to the removal code  208 , in order to discourage malicious “replacement ” messages which are actually sent to delete unrelated earlier messages. 
     A fourth category of indicators  306  includes indicators  210  which control automatic message  206  removal according to whether a storage limit has been reached. For instance, an indicator  306  may specify that the message  206  is to be deleted automatically by the removal code  208  from each recipient&#39;s mailbox/inbox after the number of saved messages in a specified folder reaches one thousand, or after the amount of disk space taken by the saved messages reaches three megabytes, or when the disk partition has less than one megabyte of free space left. 
     A given indicator  210  may belong to more than one category. For instance, an indicator may specify that the message is to be automatically removed when a replacement message arrives or one week after being opened, whichever occurs first. 
     More generally, FIG. 3 illustrates methods for using self-removing messages  206  to make email messaging more convenient for message recipients by shifting the burden of message removal from the message recipient  202  to at least one of the message originator  200  and the message distributor  222 . Through removal indicators  210  and/or removal code  208  which is associated with message content  212  by the message originator  200  and/or the message distributor  222 , the methods provide the message originator  200  and/or the message distributor  222  with initial control over the deletion of a recipient copy of the message content  212  after that content and the self-removal enhancement reach the recipient  202 . Unlike prior approaches, the message content copy at the recipient&#39;s location may be automatically deleted in response to various criteria, even if the message containing the content  212  has already been opened by the recipient  202 . As with other methods of the invention, the methods illustrated by FIG. 3 may be embodied in software which configures a computer storage medium such as a CD, floppy disk, hard drive, ROM, or RAM. 
     The methods associate message content  212  with a self-removal enhancement such as one or more self-removing message indicators  210 . The association between the message contents  212  and the self-removal enhancement is made by the message originator  200 , by the message distributor  222 , or both. It may be performed by placing removal code  208  in the message (e.g., as an attachment). But it is preferably performed by placing one or more removal indicators  210  in the message (e.g., in an email header or an email subject line) with the content  212 . 
     In alternative embodiments, the method does not place the self-removal enhancement in the same message as the content  212  that is thus made subject to removal. Instead, the method may associate message content  212  with a self-removal enhancement by placing the enhancement in an email message  206  which identifies a separate message, if the content  212  is provided in the separate message. That is, the association may be made by sending the email message contents  212  in one partial transmission  218  to the recipient  202  and sending the self-removal enhancement in a separate partial transmission  218  (before or after the content  212  is sent), and by ensuring that the enhancement portion of the transmission  218  permits identification of the intended content  212 . For instance, an ISP  222  may transmit to its member email tools  226  an instruction which indicates that any subsequent message from an email address specified in the instruction should be subject to automatic removal one day after being opened, and that the recipient should be warned of this when such a message is opened. 
     As with other methods of the invention, the methods illustrated in FIG. 3 may be used with various types of content  212  in a variety of private, governmental, and/or commercial contexts. If the contents  212  include advertising, for instance, then the methods may obtain an email address for the recipient  202  from an email address database containing many addresses. Of course, the contents  212  may contain various types of information, including advertisements, notices, news items, links to a web site, and other content, including content identified elsewhere herein and/or content used in conventional messaging systems and methods. 
     Inventive methods may be employed by the distributor  222 , or by an authorized agent/subcontractor/service/etc. acting for the distributor  222 , to verify that self-removing messages  206  are being used to shift the burden of message removal from message recipients  202 . For instance, as indicated generally in FIGS. 2 and 3, in some systems the distributor  222  receives at one or more intermediate nodes  220  a message intended for the recipient  202 . The distributor  222  etc. may use software  208  to check the message to determine whether the message contains a self-removing message indicator  210 . This may check for a particular indicator  210 , or for more than one indicator  210 , or for at least one indicator  210  from a specified group of indicators  210 . Checks for indicator(s)  210  may be performed by reading the email header, email subject line, and/or other expected location(s) of the indicator(s)  210 . 
     The check for a self-removal enhancement in a given message may be triggered by one or more one predetermined check triggering criteria which indicate that a self-removing message indicator  210  should be present. A self-removing message indicator  210  itself is not a triggering criterion. In some cases, an indicator  210  or other self-removal enhancement is expected because the message is from an entity that has an agreement with the distributor  222  permitting mass mailings through the distributor  222  subject to use of the self-removal enhancement. For instance, the message may come from a source address on a list of advertisers who have mailing contracts with the distributor  222  or a license to use the distributor&#39;s membership email database. 
     In other cases, a self-removal enhancement is not expected but should nonetheless be present because the message is part of an unauthorized mass mailing. The check triggering criteria may include criteria for detecting “spam ” email through random sampling, conventional traffic monitoring, suspicious address monitoring, and the like. For instance, the message may contain keywords or phrases that suggest it should be subject to automatic removal for the recipients&#39; convenience. The message may have come from a source address that is sending a large number of messages in a short time, or from an address that is responsible for numerous messages to nonfunctional destination addresses (“bounced ” messages arising from use of an email database containing many incorrect or obsolete addresses). 
     In short, check triggering criteria used by or for the distributor  222  may identify the message as one that originates with an authorized advertiser or another authorized entity. In this case, the invention allows the distributor  222  to monitor compliance with distributor contracts and/or policies, laws, or regulations that require automatic message removal. Check determining triggering criteria may also identify the message as one that originates as part of a mass mailing that was not expressly authorized. In that case, the invention provides the distributor  222  with an option less extreme than the conventional choice of either (i) allowing the mailing to continue as is, or (ii) attempting to block it entirely. Instead, the messages that were not previously self-removing can be modified by or for the distributor  222  to add a self-removal enhancement, so that recipients  202  receive the messages but are not unduly inconvenienced by them. Conversely, the distributor  222  etc. may strip out self-removal enhancements, so that messages  206  are modified to become not self-removing. 
     If the checking step at the node  220  determines that the message contains or is otherwise subject to a self-removing message indicator  210  as expected, then the node  220  transmits the message  206  on toward the recipient  202 . But if the checking step determines that the message does not contain indicator(s)  210  as expected, then the message may be blocked to prevent further transmittal to the recipient  202 , e.g., by being deleted, dropped, or rerouted back to the originator. Alternately, the lack of expected indicator(s)  210  may be remedied by inserting one or more indicators  210  in the message and then transmitting the resulting message  206  from the intermediate node  220  toward the recipient  202 . 
     At the recipient  202  (e.g., at the recipient&#39;s mail server and/or at the recipient&#39;s laptop, wireless device, or other workstation), removal code  208  checks incoming messages to determine whether they contain any self-removing message indicators  210  from message originators  200  and/or message distributors  222 . The removal code  208  then automatically notifies the recipient  202 , removes messages  206 , and otherwise proceeds in response to such indicators  210  with each message  206  which contains or is otherwise associated with an indicator  210 . Note that deletion instructions provided by the recipient  202  are not indicators  210 , since they do not give originators  200  and/or distributors  222  responsibility for, and initial control over, removal of messages at the recipient&#39;s location. 
     Additional Examples 
     Additional details regarding various embodiments of the present invention are provided below; “embodiment ” refers to any system, method, signal, or configured medium according to the invention. Discussions of a given embodiment also apply to other embodiments unless indicated otherwise to one of skill in the art. 
     In one embodiment, a self-removing email file includes several message components  206  which display themselves in groups of one or more components each, and then self-remove  234  the displayed  232  components. The display  232  of a given group may be triggered by an event such as arrival at the recipient&#39;s system  226 , the opening of an outer email envelope, the launching of a certain application, the passage of a predetermined time period, or the arrival of a predetermined date. 
     In one embodiment, a self-removing email file&#39;s self-removal property can be expressly overridden by the sender  200 , by the recipient  202 , by an intervening authority  222  such as an ISP or an authorized government agency, or by some combination of these. In some cases, the override is silent, and in others the sender  200  or recipient  202  or both are automatically notified of the override. 
     In some embodiments, a reply email (self-removing or not) is sent  236  automatically to the sender  200  when the recipient  202  has opened the self-removing email message  206 . In some cases, the possibility of a reply is an explicit option presented to the user  200  or  202 ; in some of these cases, the options presented include one to send  236  a reply asking that the recipient  202  be removed from the mailing list. This allows the recipient  202  to request removal by doing little or nothing more than opening the unsolicited message  206  and clicking on a “REMOVE FROM MAILING LIST ” box or button. In some embodiments, the recipient  202  is given the option of inserting text or other digital material in the reply. 
     In one embodiment, a message to be emailed is embedded in an executable (interpretable, etc.) file and the file  206  is emailed. When the recipient  202  tries to open the message  206  the executable portion runs an authentication operation  228 . If the recipient  202  is authorized and the message file  206  has not already been opened, then an executable portion  214  of the file  206  and/or a conventional part of the recipient station  226  displays  232  the message. The message  206  then deletes itself, thereby deleting the displayed copy of the message and preventing the code that did the display from redisplaying the message later. The deletion  234  may include an electronic shredding form of deletion, which overwrites the file (possibly several times) rather than merely marking it as free. 
     In one embodiment, the displaying portion  214  of the executable code and the deleting portion  208  of the executable code are executed as one atomic operation, with the atomicity enforced by the operating system and/or by the particular processor on which the message file  206  executes. Tools and techniques for enforcing atomicity are well known, in the database arts and elsewhere. 
     In one embodiment, the message file  206  incrementally overwrites itself while incrementally displaying  232  its message, with the overwriting and displaying increments interleaved in their operation. After decrypting  230  the message to form a block of message content  212  bytes in RAM, execution of displaying code  214  and removing code  208  is interleaved as follows. The embodiment exchanges the video display bytes (which are something other than the message content  212 ) with the message content bytes (which are placed in a format used by the video display buffer). Several bytes at a time may also be thus exchanged. Each exchange displays another increment of the message and also overwrites part of the message content  212  with whatever was previously being displayed. 
     In one embodiment, the message file  206  loads itself into memory, deletes itself from disk in partial or complete performance of an active removal step  234 , verifies the deletion, and only then performs the display operation  232 . Concurrently with or shortly after the display, the message file may additionally overwrite itself in memory to complete step  234 . 
     Tools and techniques familiar to those of skill in the art for self-modifying code and/or self-deleting programs such as self-deleting scripts or self-deleting installers may be helpful during implementation of particular embodiments of the invention. Likewise, techniques used in Trojan horses, worms, viruses, and other programs which hide and/or propagate themselves may be modified for use in inventive email message files  206  which destroy themselves after displaying the message they carry. For instance, tools and techniques such as those employed in U.S. Pat. No. 5,623,600 may be adapted for use in the present invention. 
     In some embodiments, the message file  206  installs the message content  212  (or the entire message file  206  itself) in locations on the hard disk and/or in memory which are subject to frequent overwriting once deallocated. Suitable locations include unused clusters temporarily marked as allocated in file allocation tables, or swap files, or portions of RAM that are overwritten or scrambled during a reboot. After displaying its embedded message, the embodiment then marks itself (or at least the portion containing the message) as deallocated and forces overwriting during step  234 . For instance, the embodiment may force a reboot to scramble or overwrite RAM containing the message or mark temporarily allocated clusters free once more. 
     The message content  212  may be encrypted so it cannot be read by simply viewing the message file  206  in a debugger and looking for strings. During authentication  228 , the message file  206  may also require a password or key from the recipient  202  before decrypting  230  and displaying  232  the message. 
     Alternatively, the message file  206  may be self-decrypting (similar in spirit to self-extracting ZIP files) once it has verified its current location  226  as the one corresponding to the intended recipient  202 . Thus, copies on ISP servers or other intermediate network nodes remain encrypted, but the copy of the message file  206  at the recipient&#39;s network address will decrypt  230  when launched. 
     Network addresses, environmental parameters such as the surrounding processor and operating system, previously sent ID files, digital certificates, tokens (software or hardware), and other means can be used by the message file  206  to determine its present location. For instance, this can be done by checking the current IP or other network address against an address specified (directly or in terms of an email address) by the sender  200 . If the email connection is available, a packet can also be sent to a specified location and the address on the response packet can be examined. Of course, the recipient&#39;s environment is not always fully known, and it can be imitated. But imposing “proper location ” as a requirement for message content  212  display  232  makes it harder to gain unauthorized access to those contents  212 . 
     In some embodiments, means are used to make the use of a debugger generally, and the use of break points or trace points in particular, result in self-destruction of the message file  206  without display of the message contents  212 , or at least in a failure to decrypt and display the message content  212 . Suitable means  216  include (a) timed loops with conditionals that change behavior based on the time required to execute the loop (debugging is detected as unusually slow execution); (b) checksums on the current code  208  in memory (insertion of breakpoints alters the checksum); and (c) the interrupt vector table is temporarily modified to ignore keyboard and mouse input and hence disable debugger commands (the message content  212  is displayed a preset period of time and then disappears forever). 
     In some embodiments, steps are taken by the security code  216  to disable the Print Screen or similar command. For instance, a search for recognized print screen routines can be made and they can be temporarily disabled. Likewise, the interrupt vector table can be temporarily modified to limit input and hence disable print screen commands. 
     In some embodiments, the message file  206  checks as much of the local environment as possible for other copies of itself and permanently deletes  234  them before displaying  232  the message content  212 . Some embodiments only search for the message&#39;s file name in other directories, while other embodiments search for files of the same length or recently created files and then examine those files more closely, in case the copy has been renamed. Techniques used to identify viruses can also be modified to help the message file  206  identify copies of itself. 
     In some embodiments, techniques used in so-called “copy protection schemes ” are used by the security code  216  to help prevent copying of the message file  206 . The techniques are modified to allow copying by network system software as necessary for the message file  206  to travel across the network  100  from the originator  200  to the authorized recipient(s)  202 . 
     One embodiment does not initially delete itself after displaying the message contents  212 . Instead, the message file  206  removal code  208  self-modifies to become a searcher. The searcher has a limited life span, measured either by elapsed time since its inception or by the number of times the searcher or its direct ancestors have been launched for execution. 
     Thus, the first time the message file  206  is run, it displays  232  the message content  212 , overwrites the message content  212 , and notes internally that it has done so. The next N−1 times it is launched, it runs as a searcher. The searcher displays a dummy message such as “Decrypting message; please wait . . . ” to gain time while actually searching for other copies and permanently deleting  234  them. After finishing the search (and performing any appropriate deletions), the searcher displays a message such as “Decryption failed. Please contact X for assistance. ” X might be the message originator  200 , the message recipient  202 , or both, and/or their corresponding system administrators. The Nth time the searcher is run, the message file (searcher) permanently deletes  234  itself. In a variation, the searcher  206  spawns additional searchers that behave in a similar manner. 
     In one embodiment, a timestamp representing a limited life span is embedded in the message file  206 , and if the current time (as indicated by a call made on the recipient&#39;s system) indicates that the intended life span has elapsed, then the message file simply deletes itself without displaying the message contents. Tools and techniques such as those employed in U.S. Pat. No. 5,786,817 may be adapted for use in the present invention. 
     Signals 
     Although particular methods and systems embodying the present invention are expressly illustrated and described herein, it will be appreciated that apparatus, signal, and article embodiments may be formed according to methods and systems of the present invention. Unless otherwise expressly indicated, the description herein of methods of the present invention therefore extends to corresponding apparatus, signal, and articles, and the description of apparatus, signals, and/or articles of the present invention extends likewise to corresponding methods. 
     For instance, the message  206  may embody novel signals such as the self-removal indicators  210 , and/or the various codes such as removal code  208  for performing the removing step  234 , display code  214  for performing the displaying step  232 , and security code  216  for performing the authenticating step  228  or other security-enhancing steps such as disabling print screen or debugger functions. The signals may be embodied in “wires ”  118 , RAM, disk, or other storage media or data carriers. 
     Articles of manufacture within the scope of the present invention include a computer-readable storage medium in combination with the specific physical configuration of a substrate of the computer-readable storage medium. The substrate configuration represents data and instructions which cause the computers to operate in a specific and predefined manner as described herein. Suitable storage devices include floppy disks, hard disks, tape, CD-ROMs, RAM, flash memory, and other media readable by one or more of the computers. Each such medium tangibly embodies a program, functions, and/or instructions that are executable by the machines to perform self-removing message creation, transmission, removal, display or other method steps substantially as described herein, including without limitation methods which perform some or all of the steps illustrated in FIG.  2 . To the extent permitted by applicable law, programs which perform such methods are also within the scope of the invention. 
     Summary 
     In summary, the present invention provides a novel way to protect confidential and proprietary email message contents without substantially reducing the ease and convenience of email transmission. In fact, the ease of use for email recipients is increased, because they no longer need to imprecisely filter or manually remove unsolicited notices or advertisements. Message originators also have more control over the persistence of their messages after the messages are sent, even if messages have been opened. ISPs and other distributors can verify and/or insert self-removal instructions to make sure that directed mailings to their members comply with automatic removal requirements. 
     Increased security is achieved, for instance, when email messages are embedded in executable files, each of which displays its particular message once and then permanently deletes itself and any copies of itself it can find. The message files may be embodied in computer storage media or (while in transit) in network connections. 
     One embodiment employing message files at least for increased security according to the invention includes the following: 
     uninstaller tools and techniques as a means for locating copies of the message file; 
     copy protection tools and techniques as a means for preventing creation of copies of the message file except as needed by the message file originator&#39;s email sending software, by the network transmission software, and by the intended recipient&#39;s email receiving software; 
     encryption tools and techniques as a means for encrypting the message contents in the message file and decrypting the message contents as part of an atomic display-and-self-destruct step; 
     virus detection tools and techniques, and uninstaller software tools and techniques, each as a means for locating unauthorized or no longer needed (e.g., copies made along the network transmission path after the received message has been displayed) copies of the message file (or of an extracted message) to be permanently deleted; 
     electronic file shredder tools and techniques as a means for permanently deleting (erasing, removing, destroying) unauthorized or no longer needed copies of the message file; 
     self-modifying code tools and techniques as a means for deleting the message file as the message is being displayed and/or for modifying the message file to spawn and manage searcher computer processes which seek out and permanently delete unauthorized or no longer needed copies of the message file; 
     anti-reverse engineering and obfuscation tools and techniques, and digital signature or checksum tools and techniques, and interrupt manipulation tools and techniques, each as a means for protecting the integrity and security of the message file contents prior to authorized display of the message, each possibly in conjunction with encryption tools and techniques; and 
     email and networking tools and techniques as a means for authorized copying and transmission of the intact message file from the originator to the intended and authorized recipient. 
     A particular order and grouping may be indicated in examples for method steps of the invention. However, those of skill will appreciate that the steps illustrated and discussed in this document may be performed in various orders, including concurrently, except in those cases in which the results of one step are required as input to another step. For instance, deletion from disk during step  234  may precede display of the message during step  232 , and may be filed by or interleaved with deletion of message contents  212  from RAM. Likewise, steps may be omitted unless called for in the claims, regardless of whether they are expressly described as optional in this Detailed Description. For instance, encryption steps, anti-debugger steps, and screen print disabling steps are all optional actions by the security code  216 , which is itself an option component in the message  206 . Steps may also be repeated (e.g., transmittal between nodes during step  218 ), or combined (e.g., atomic display and removal steps  232  plus  234 ), or named differently. 
     The invention may be embodied in other specific forms without departing from its essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Headings are for convenience only, and are not limiting. Trademarks used herein are the property of their respective owners. Any explanations provided herein of the scientific, legal, or other principles employed in the present invention are illustrative only. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.