Abstract:
An email is created that includes one or more destination email addresses, plus historical information regarding previously exchanged emails. Before sending this email, each of the destination email addresses is checked against the email addresses in the historical information and, if a destination email address (or the domain name of that destination address) is not found in the historical information, then a warning is displayed to alert the user to the fact that this historical information may be sent to an unintended recipient. In response to this warning, which may include a list of unapproved destination email address, the user may approve a previously unapproved destination email address, change the unapproved destination email address to one that has been previously approved, or enter a new distribution email to be substituted for the unapproved one. When creating the email, the user may also specify other approved email addresses.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Pursuant to 35 U.S.C. 119, Applicant claims a right of priority to Japanese Patent Application No. 2009-105837 filed 24 Apr. 2009. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to computers, methods and computer program products wherein destination email addresses are checked against historical email address information to prevent an email from being sent to an unintended recipient. 
         [0003]    With the rapid progress of Internet technology, information has been frequently exchanged using emails. Upon receiving an email, the recipient may respond by creating an email that includes historical information regarding other emails previously exchanged between multiple users, including the received email. An email containing historical information may include a header containing a destination email address, a body containing the message to be sent, and a historical information section citing emails exchanged between multiple users. In the case where multiple users have exchanged emails containing historical information with each other several times, this historical information section may become enormous, making it difficult for the user to check and grasp all the historical information. For this reason, when sending an email containing historical information, the user may send the email to an unintended destination, to which the sender does not want to disclose the historical information. 
         [0004]    In view of the foregoing, numerous email sending methods have been developed to prevent the user from sending an email to an unintended destination. For example, a user terminal disclosed in Japanese Published Unexamined Patent Application No. 2007-193717 (“Patent Document 1”) includes an address book that stores email addresses and identification data such as the names, prefixes, company names, section names, job titles, postal addresses, and photos or illustrations of the owners of the email addresses. Each email address is associated with corresponding identification data and send/receive history data, such as the send/receive frequencies of previous emails and the send/receive dates and times. Before sending an email, the user terminal checks the data to be sent, which contains a destination email address, a destination name, an email body and the like, against the address book and the send/receive history file, so as to extract identification data and send/receive history data corresponding to the destination email address to give a warning to the user if necessary. 
         [0005]    While the email sending method disclosed in Patent Document 1 includes determining whether a destination email address is stored in the address book, it does not include determining whether the destination email address is an intended destination to which the user is permitted to disclose the historical information section of the email. Accordingly, as long as the unintended destination is an email address stored in the address book, the email containing the historical information may be sent to even unintended destinations to which the users does not need or want to disclose the historical information. This presents the problem of indiscriminately disclosing historical information. 
         [0006]    For example, assume that a user “A” has exchanged emails containing historical information on several occasions with a user B (in the company) and a user C (outside the company), whose email addresses are stored in the address book and that, in reply to a received email, the user A sends an email containing historical information that cites the received email. If the user A selects a user D (outside the company), whose email address is stored in the address book, as the reply destination and attempts to send the email containing the historical information thereto, the email sending method disclosed in Patent Document 1 will send the email to the user D. This is because the user D is stored in the address book and is therefore handled as users B and C are handled. As a result, disadvantageously, the contents of the email containing the historical information that user A has several times exchanged emails with users B and C will leak to user D, failing to maintain confidentiality. 
       SUMMARY 
       [0007]    An apparatus according to a first aspect of the present invention includes: an email creation unit that creates an email containing historical information citing an email exchanged between a plurality of users; an address information collection unit that collects, as address information, a part or all of an email address contained in the historical information cited in the created email; an address information storage unit that stores the collected address information; a destination checking unit that checks whether a destination email address set in the email containing historical information contains the stored address information; and a warning information output unit that outputs warning information indicating that the destination email address does not contain the address information. 
         [0008]    The apparatus according to the first aspect of the present invention preferably further includes an approval receiving unit that receives input of send approval information indicating approval for sending to an email address corresponding to the warning information outputted from the warning information output unit. 
         [0009]    In the apparatus according to the first aspect of the present invention, the approval receiving unit may receive input of at least one of a domain name, a sub-domain name, and an email address as input of the send approval information. 
         [0010]    The apparatus according to the first aspect of the present invention preferably further includes a destination change unit that changes an email address corresponding to the warning information outputted from the warning information output unit. 
         [0011]    In the apparatus according to the first aspect of the present invention, a header of the created email containing historical information may contain at least one of a domain name, a sub-domain name, and an email address as the send approval information. 
         [0012]    In the apparatus according to the first aspect of the present invention, the address information collection unit may collect the address information from the email exchanged between the plurality of users before the email containing historical information is created. 
         [0013]    In the apparatus according to the first aspect of the present invention, the address information may be a domain name. 
         [0014]    A method according to a second aspect of the present invention is a method executable by a computer configured to send or receive an email. The method includes: creating an email containing historical information citing an email exchanged between a plurality of users as historical information; collecting, as address information, a part or all of an email address contained in the history information cited in the created email containing historical information; storing the collected address information; checking whether a destination email address set in the email containing historical information contains the stored address information; and outputting warning information indicating that the destination email address does not contain the address information. 
         [0015]    The method according to the second aspect of the present invention preferably further includes receiving input of send approval information indicating approval for sending to an email address corresponding to the outputted warning information. 
         [0016]    In the method according to the second aspect of the present invention, input of at least one of a domain name, a sub-domain name, and an email address may be received as input of the send approval information. 
         [0017]    The method according to the second aspect of the present invention preferably further includes changing an email address corresponding to the outputted warning information. 
         [0018]    In the method according to the second aspect of the present invention, a header of the created email containing historical information may contain at least one of a domain name, a sub-domain name, and an email address as the send approval information. 
         [0019]    In the method according to the second aspect of the present invention, the address information may be collected from the email exchanged between the plurality of users before the email containing historical information is created. 
         [0020]    In the method according to the second aspect of the present invention, the address information may be a domain name. 
         [0021]    A computer program product according to a third aspect of the present invention is a computer program product executable by a computer configured to send or receive an email. The computer program product causes the computer to function as: email creation means that creates an email containing historical information citing an email exchanged between a plurality of users as historical information; address information collection means that collects, as address information, a part or all of an email address contained in the historical information cited in the created email containing historical information; address information storage means that stores the collected address information; destination checking means that checks whether a destination email address set in the email containing historical information contains the stored address information; and warning information output means that outputs warning information indicating that the destination email address does not contain the address information. 
         [0022]    The computer program product according to the third aspect of the present invention preferably causes the computer to further function as approval receiving means that receives input of send approval information indicating approval for sending to an email address corresponding to the warning information outputted from the warning information output means. 
         [0023]    In the computer program product according to the third aspect of the present invention, the approval receiving means may be caused to function as means that receives input of at least one of a domain name, a sub-domain name, and an email address as input of the send approval information. 
         [0024]    The computer program product according to the third aspect of the present invention preferably causes the computer to further function as destination change means that changes an email address corresponding to the warning information outputted from the warning information output means. 
         [0025]    In the computer program product according to the third aspect of the present invention, a header of the created email containing historical information may contain at least one of a domain name, a sub-domain name, and an email address as the send approval information. 
         [0026]    In the computer program product according to the third aspect of the present invention, the address information collection unit may be caused to function as means that collects the address information from the email exchanged between the plurality of users before the email containing historical information is created. 
         [0027]    In a fourth aspect of the invention, a method, apparatus and computer program product is described in which a first email is created that comprises a header and historical information, the header comprises a first destination email address, and the historical information comprises a historical email address for a previously exchanged email. At least a portion of the historical email address contained in the historical information is stored as a first approved address. The first approved address is compared to a corresponding portion of the first destination email address and, in response to the corresponding portion of the first destination email address being different from the first approved address, a warning is outputted. 
         [0028]    In a case where multiple users exchange emails containing historical information with each other, the present invention checks whether a destination email address of the email containing historical information contains address information indicating a part or all of an email address contained in the cited history information. This can prevent the historical information from being sent to an unintended destination, to which the user does not need to disclose the cited history information, thereby maintaining confidentiality. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0029]      FIG. 1  is a block diagram showing an exemplary configuration of an email address checking apparatus according to a first embodiment of the present invention that checks the destination email addresses of emails containing historical information. 
           [0030]      FIG. 2  is a drawing showing the structure of an email containing historical information according to the first embodiment. 
           [0031]      FIG. 3  is a diagram showing functional blocks of the email address checking apparatus according to the first embodiment. 
           [0032]      FIG. 4  is a flowchart showing the process steps performed by a CPU of the email address checking apparatus according to the first embodiment. 
           [0033]      FIG. 5  is a drawing illustrating an operation window for giving send approval, of the email address checking apparatus according to the first embodiment. 
           [0034]      FIG. 6  is a drawing illustrating an operation window for changing destination email addresses, of the email address checking apparatus according to the first embodiment. 
           [0035]      FIG. 7  is a drawing illustrating an operation window for adding a domain name, to which the user wishes to give send approval, of the email address checking apparatus according to the first embodiment. 
           [0036]      FIG. 8  is a drawing illustrating the header of an email containing historical information additionally containing domain names, to which the user wishes to give send approval, according to the first embodiment. 
           [0037]      FIG. 9  is a flowchart showing the process steps performed by a CPU of an email address checking apparatus according to a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    The embodiments described below are not intended to restrict the invention as set forth in the appended Claims. Also, not all elements described in these embodiments are essential to the invention. The present invention can be carried out in many different modes and should not be construed as being limited to the descriptions of the embodiments described below. Same elements are given same reference numerals throughout the specification and drawings. 
         [0039]    Referring now to the accompanying drawings, there will be specifically described an email address checking apparatus according to a first embodiment of the present invention that checks whether, with respect to an email containing historical information that cites emails previously exchanged between multiple users, a destination email address in the email includes a part or all of an email address contained in the historical information. 
         [0040]    In the first embodiment, an email address checking apparatus preferably obtained by installing a computer program into a computer system will be described. However, as is apparent for those skilled in the art, a part of the present invention may be carried out as a computer program executable by a computer. Accordingly, the present invention can be embodied as hardware, which is an apparatus that checks a destination email address set in an email containing historical information, as software, or a combination of software and hardware. The above-mentioned computer program may be stored in any computer-readable storage medium, such as a hard disk, a digital versatile disc (DVD), a compact disc (CD), an optical storage device, or a magnetic storage device. 
         [0041]    The first embodiment checks whether a destination email address contains the domain name of an email address contained in the historical information cited in the email. This can prevent the email containing the historical information from being sent to an unintended destination, to which the user does not need or want to disclose the cited historical information, thereby maintaining confidentiality. 
         [0042]      FIG. 1  is a block diagram showing an exemplary configuration of an email address checking apparatus  1  according to a first embodiment of the invention, which checks the destination email addresses of emails containing historical information. The email address checking apparatus  1  may be connected to multiple computers  3  via a network  2  so that this email address checking apparatus can perform data communications with these computers. The email address checking apparatus  1  sends or receives emails containing historical information to and from the computers  3  with one of the computers functioning as an email server. 
         [0043]    The email address checking apparatus  1  may include a central processing unit (CPU)  11 , a memory  12 , a storage unit  13 , an I/O interface  14 , a video interface  15 , a transportable disk drive  16 , a communication interface  17  and an internal bus  18  that connects these hardware components. The CPU  11  is connected to the above-mentioned hardware components of the email address checking apparatus  1  via the internal bus  18 . The CPU  11  controls the operations of the hardware components, as well as performs various software functions in accordance with a computer program  100  stored in the storage unit  13 . The memory  12  may be a volatile memory, such as a static random access memory (SRAM) or synchronous dynamic random access memory (SDRAM). In executing the computer program  100 , a load module is loaded into the memory  12 , which in turn stores temporary data or the like generated by execution of the computer program  100 . 
         [0044]    The storage unit  13  may include a built-in, fixed storage device (hard disk), a read-only memory (ROM), or the like. The computer program  100  may be downloaded from a transportable storage medium  90 , such as a DVD or CD-ROM, using the transportable disk drive  16  and stored in the storage unit  13 . For execution, the computer program  100  is loaded from the storage unit  13  into the memory  12  and executed. The computer program  100  may be downloaded from one of the external computers  3  via the communication interface  17 . The storage unit  13  includes a domain name storage unit  131 . As will be described later, the domain name storage unit  131  stores the domain names of email addresses contained in the historical information section of an email. 
         [0045]    The structure of an email containing historical information will now be described in detail.  FIG. 2  is a drawing showing the structure of an email containing historical information according to the first embodiment. Referring to this figure, an email containing historical information consists of a header  201  containing a destination email address as a major component, a body  202  containing the message to be sent, and a historical information section  203  containing cited history information. A portion  203   a  of the historical information section  203  consists of the header and body of a received email, and a portion  203   b  thereof is the historical information section of the received email. 
         [0046]    In the first embodiment, an email address consists of a local name, a sub-domain name, and a domain name. For an email address “satoh@jp.hoge2.com”, “satoh” is the local name, “jp” is the sub-domain name, and “hoge2.com” is the domain name. 
         [0047]    Returning to  FIG. 1 , the communication interface  17 , which is connected to the internal bus  18 , is connected to the external network  2 , such as the Internet, a LAN or a WAN. Thus, the email address checking apparatus  1  can send and receive data to and from the external computers  3  and the like. The I/O interface  14  is connected to data input devices, such as a keyboard  21  and a mouse  22 , to receive data input. The video interface  15  is connected to a display device  23 , such as a CRT monitor or LCD, to display images. 
         [0048]    The operation of the email address checking apparatus  1  will now be described. 
         [0000]      FIG. 3  is a diagram showing functional blocks of the email address checking apparatus  1  according to the first embodiment. Referring to this figure, in order to reply to or forward a received email, an email creation unit  301  creates an email containing historical information that cites emails exchanged between multiple users, including the received email, while receiving input using the keyboard  21  or mouse  22 . 
         [0049]    A domain name collection unit  302  collects the domain name of an email address from the historical information section  203  of the email created by the email creation unit  301 . Specifically, if the historical information section  203  contains an email address “satoh@jp.hoge2.com”, the domain name collection unit  302  collects the domain name thereof “hoge2.com”. If the historical information section  203  contains multiple email addresses, the domain name collection unit  302  collects multiple domain names thereof, except for duplicates. 
         [0050]    The domain name storage unit  131  stores the domain name collected by the domain name collection unit  302  in such a manner that the domain name is associated with the corresponding email containing the historical information. If the domain name collection unit  302  collects multiple domain names, the domain name storage unit  131  stores the domain names in such a manner that the domain names are associated with the corresponding single email containing the historical information. 
         [0051]    A destination checking unit  303  checks whether the destination email address (reply destination or forward destination) set in the created email containing the historical information contains the domain name stored in the domain name storage unit  131 . For example, if the historical information  131  stores the domain name “hoge2.com”, the destination checking unit  303  checks whether the destination email address set in the email contains the domain name “hoge2.com.” 
         [0052]    If there are multiple destination email addresses, and if the destination checking unit  303  reveals that all the destination email addresses contain a domain name that&#39;s stored in the domain name storage unit  131 , the sending processing unit  304  sends the email containing the historical information to the computers  3  via the network  2 . 
         [0053]    However, if after checking the destination email addresses the destination checking unit  303  reveals that the domain name of a destination email address is not stored in the domain name storage unit  131 , a warning output unit  305  outputs a warning to the display device  23  indicating that sending the email to the destination email address is not approved. The method for outputting a warning is not limited to displaying the warning on the display device  23 , as other methods such as sounding of an alarm may be used. 
         [0054]    An approval receiving unit  306  receives input of send approval information indicating approval for sending to the destination email address corresponding to the warning outputted from the warning information output unit  305 . The send approval information may be inputted by clicking on a button using the mouse  22  or may be inputted via the keyboard  21 . 
         [0055]    A destination change unit  307  changes the destination email address corresponding to the warning outputted from the warning information output unit  305 . The destination email address may be changed by clicking on a different destination email address using the mouse  22 , or it may be changed by directly entering a new destination email address using the keyboard  21 . 
         [0056]    When approval is given to send the email to the destination email address corresponding to the warning outputted from the warning information output unit  305 , or the destination email address is changed to an email address required as a destination, the sending processing unit  304  sends the email containing the historical information to the computers  3  via the network  2 . 
         [0057]      FIG. 4  is a flowchart showing the process steps that the CPU  11  of the email address checking apparatus  1  performs, according to the first embodiment. In order to reply to or forward a received email, the CPU  11  of the email address checking apparatus  1  creates an email containing the historical information of emails previously exchanged between multiple users, including the received email, on the basis of input from the keyboard  21  or mouse  22  (step S 401 ). 
         [0058]    The CPU  11  collects the domain name of an email address contained in the historical information section  203  of the created email (step S 402 ). If the historical information section  203  contains multiple email addresses, the CPU  11  collects the multiple domain names thereof, except for duplicates. The CPU  11  stores the collected domain name in such a manner that the domain name is associated with the created email (step S 403 ). 
         [0059]    The CPU  11  checks whether all destination email addresses in the created email contain a domain name stored in the domain name storage unit  131  (step S 404 ). If there are multiple destination email addresses and if multiple domain names are stored, the CPU  11  checks whether each of the destination email addresses contains one of the domain names stored in the domain name storage unit  131 . If the CPU  11  determines that all the destination email addresses contain one of the domain names stored in the domain name storage unit  131  (YES in step S 404 ), it sends the created email containing the historical information to the computers  3  via the network  2  (step S 405 ). 
         [0060]    If the CPU  11  determines that there exists destination email addresses having domain names that are not stored in the domain name storage unit  131 (NO in step S 404 ), it outputs a warning to the display device  23  that some of the destination email addresses do not contain a stored domain name (step S 406 ). 
         [0061]    The CPU  11  approves sending the email containing the historical information to the destination email addresses corresponding to the warning in response to a user input made via the keyboard  21  or mouse  22 , or changes the destination email addresses corresponding to the warning (step S 407 ). When completing the above-mentioned approval or change, the CPU  11  sends the email containing the historical information to the computers  3  via the network  2  (step S 405 ). 
         [0062]    An operation to approve sending the email to the destination email addresses corresponding to the outputted warning will now be described.  FIG. 5  is a drawing illustrating an operation window for giving send approval of the email address checking apparatus  1  according to the first embodiment. Referring to this figure, the CPU  11  provides a warning indicating that at least one destination email address does not contain a domain name stored in the domain name storage unit  131  by displaying (preferably, on display device  23 ) a “check destination” warning window  500 . The “check destination” warning window  500  is a window for indicating a warning, as well as a window for receiving send approval and a destination email address change. The “check destination” window  500  includes an approved destination section  501  and an unapproved destination section  502 . The approved destination section  501  displays destination email addresses containing the domain name stored in the domain name storage unit  131 . The unapproved destination section  502  displays destination email addresses not containing a domain name stored in the domain name storage unit  131 . 
         [0063]    The approved destination section  501  and unapproved destination section  502  display each email address hierarchically in the order of the domain name, sub-domain name, and local name. For an email address “suzuki@jp.hoge2.com”, its domain name “hoge2.com” is displayed in the first level, its sub-domain name “jp” is displayed in the second level, and its local name “suzuki” is displayed in the third level. Displayed below the domain name “hoge2.com” of the first level is the sub-domain name “jp” of the second level, as well as a sub-domain name “us” of the second level. Displayed below the sub-domain name “us” of the second level is a local name “takahashi” of the third level. Displayed below the sub-domain name “jp” of the second level is a local name “suzuki” of the third level, as well as a local name “satoh” of the third level. For an email address “tada@hoge1.co.jp” having no sub-domain name, its domain name “hoge1.co.jp” is displayed in the first level and its local name “tada” is displayed in the second level. 
         [0064]    In the unapproved destination section  502 , a checkbox is provided in front of each domain name, sub-domain name, and local name. Each checkbox, when checked, functions as an approval to send information. Specifically, by using the mouse  22  to place a checkmark in the checkbox of a domain name, sub-domain name, or local name, the user gives send approval to the destination email address on a domain name, sub-domain name, or email address basis. For example, by placing a checkmark in the checkbox  503  provided for the local name “tada”, send approval is given with respect to the email address name “tada@hoge1.co.jp.” Also, by placing a checkmark in a checkbox  504  provided for the sub-domain name “jp”, send approval is given with respect to the email address names “suzuki@jp.hoge2.com” and “satoh@jp.hoge2.com”, which both have the domain name “hoge2.com” and the sub-domain name “jp”. By pressing the send button  505  when send approval has been given with respect to all destination email addresses, the “check destination” window  500  is closed and the email containing the historical information is sent to the computers  3  via the network  2 . 
         [0065]    An operation for changing the destination email addresses corresponding to the outputted warning will now be described.  FIG. 6  is a drawing illustrating an operation window for changing destination email addresses of the email address checking apparatus  1  according to the first embodiment. Referring to  FIG. 6(   a ), the CPU  11  displays a warning indicating that destination email addresses do not contain the domain name stored in the domain name storage unit  131  by displaying on display device  23  the “check destination” window  500 . Hereafter, a case where the email address “takahashi@us.hoge2.com” is displayed in the unapproved destination section  502  of the “check destination” window  500  is changed to “takahashi@temp.co.jp” will be described. 
         [0066]    When clicking a label  600  of the local name “takahashi” using the mouse  22 , the CPU  11  displays a “change destination” window  601  on the display device  23 , as shown in  FIG. 6(   b ). The “change destination” window  601  displays the email address “takahashi@us.hoge2.com” in a box  602  for displaying an email address to be changed. The email address “takahashi@us.hoge2.com” may be changed to “takahashi@temp.co.jp” by directly editing the email address in the box  602  using the keyboard  21  or mouse  22 . 
         [0067]    As for the email address “takahashi@us.hoge2.com” displayed in the unapproved destination section  502 , the local name thereof is correct and the sub-domain name and domain name are wrong. Accordingly, the email address may be changed using multiple domain names stored in the domain name storage unit  131 . Specifically, as shown in  FIG. 6(   c ), placing a checkmark in a “select approved domain” checkbox  603  of the “change destination” window  601  causes multiple domain names stored in the domain name storage unit  131  to appear in a box  604 . Since a radio button is provided in front of each of the domain names displayed in the box  604 , the email address can be changed by clicking and selecting a domain name required as a destination using the mouse  22 . In the above-mentioned example, selection of a domain name “temp.co.jp” changes the email address to the email address name “takahashi@temp.co.jp.” 
         [0068]      FIG. 6(   d ) shows the “check destination” window  500  displayed after changing the email address to “takahashi@temp.co.jp.” In the changed “check destination” window  500 , the label  600  of the local name “takahashi” has been deleted from the unapproved destination section  502  along with the sub-domain name “us” and the label  600  of the local name “takahashi” has been displayed below the domain name “temp.co.jp” in the approved destination section  501 . By pressing the send button  505  when completing the change of the unapproved destinations to email addresses required as destinations, the “check destination” window  500  is closed and the email containing historical information is sent to the computers  3  via the network  2 . 
         [0069]    In the operations shown in  FIGS. 5 and 6 , approval for sending to the destination email addresses is given or the destination email addresses are changed, based on a warning indicating that the destination email addresses do not contain the stored domain name. However, the email creation unit  301  according to the first embodiment may previously add a domain name to which the user wishes to give send approval (approved domain name) regardless of the presence or absence of a warning. Referring now to the drawings, an operation where the email creation unit  301  previously adds an approved domain name will be described specifically.  FIG. 7  is a drawing illustrating an operation window for adding a domain name, to which the user wishes to give send approval, of the email address checking apparatus  1  according to the first embodiment. 
         [0070]    In creating an email containing historical information (email for reply or forwarding), the email creation unit  301  displays a “create message” window  700  on the display device  23 , as shown in  FIG. 7 . By receiving user input from the keyboard  21  or mouse  22 , the email creation unit  301  fills predetermined sections of the “create message” window  700  to create an email containing historical information. In adding an approved domain name to the email containing the historical information in advance, an “add destination” window  702  is displayed on the display device  23  by pressing an “add destination” button  701  of the “create message” window  700 . Entering an approved domain name (e.g., “hogehoge.com”) into a box  703  of the displayed “add destination” window  702  and pressing an “add to list” button  704  adds the approved domain name to a list box  705  (“hogehoge.co.jp” is already added to the list). 
         [0071]    Pressing an “OK” button  706  when adding all desired approved domain names in the “add destination” window  702  closes the “add destination” window  702 . By performing the above-mentioned operation, the email creation unit  301  adds the approved domain names to the header of the email containing the historical information.  FIG. 8  is a drawing illustrating the header of the email containing the historical information according to the first embodiment where domain names, to which the user wishes to give send approval, have been added. As shown in  FIG. 8 , the approved domain names (e.g., “hogehoge.com”, “hogehoge.co.jp”) added using the “add destination” window  702  are additionally disposed in an “X-Approvable-Domain” row  801  of the header of the email containing historical information. 
         [0072]    When the domain name collection unit  302  collects domain names from the email containing an email address in the historical information section, where the approved domain names have been added to the header thereof, it also collects the previously added approved domain names. For example, from the header shown in  FIG. 8 , the domain name collection unit  302  can collect the domain name of the source, “xxx.co.jp”, and the domain name of the destination, “ibbm.com”, as well as the added approved domain names “hogehoge.co.jp” and “hogehoge.com”. As seen, by adding the approved domain names to the header, sending of any email containing historical information to the approved domain names can be approved as long as the email containing historical information includes the header in the historical information section thereof. Particularly in a case where different domain names are set for the same company, adding the company&#39;s different domain names to the header as approved domain names in creating a new email will prevent appearance of a warning in exchanging an email containing historical information later, as long as the destinations thereof are intra-company addresses. 
         [0073]    As seen, in a case where multiple users exchange emails containing historical information with each other, the first embodiment checks whether the destination email address of the email containing historical information contains the domain name of an email address contained in the cited historical information. This can prevent the email from being sent to an unintended destination, to which the user does not need to disclose the cited historical information, thereby maintaining confidentiality. 
         [0074]    The present invention is not limited to the above-mentioned embodiment and various changes, modifications, and the like can be made thereto without departing from the spirit and scope of the invention. Instead of collecting the domain name of an email address contained in the historical information and checking whether the destination email address contains the domain name, it is possible to collect the sub-domain name of an email address contained in the historical information section or the entire email address and check whether the destination email address contains the sub-domain name or entire email address. Also, all the elements of the email address checking apparatus  1  shown in  FIG. 3  may be constituted by multiple computers rather than a single computer. For example, the email creation unit  301  and the domain name collection unit  302 , destination checking unit  303 , and domain name storage unit  131  may be constituted by another computer. 
         [0075]    According to a second embodiment, in the email address checking apparatus  1  according to the first embodiment, the domain name collection unit  302  collects the domain names from the historical information section of the email containing historical information created by the email creation unit  301 . However, the domain name collection unit  302  may collect domain names not only from the email containing the historical information created by the email creation unit  301 , but also from emails exchanged between multiple users before the email containing the historical information is created. Accordingly, in the email address checking apparatus  1 , the domain name collection unit  302  collects a domain name from an email address received by the email creation unit  301  will be described in a second embodiment of the present invention. The example configuration and functional blocks of the email address checking apparatus  1  according to the second embodiment are the same as those of the email address checking apparatus  1  according to the first embodiment and will not be described in detail. 
         [0076]    Note that in  FIG. 3 , the domain name collection unit  302  collects the domain name of an email address from an email received by the email creation unit  301  before the email creation unit  301  creates an email (email containing the historical information) in order to reply to or forward a received email. In a case where the email received by the email creation unit  301  consists of a header and a body, the domain name collection unit  302  collects the domain name of an email address from the header and body. Also, in a case where the email received by the email creation unit  301  consists of a header, a body, and a historical information section, the domain name collection unit  302  collects the domain name of an email address from the header, body, and historical information section. 
         [0077]      FIG. 9  is a flowchart showing the process steps of the CPU  11  of the email address checking apparatus  1  according to the second embodiment performs. The CPU  11  of the email address checking apparatus  1  collects the domain name of an email address contained in a received email (step S 901 ). The CPU  11  stores the collected domain name in such a manner that the domain name is associated with the received email (step S 902 ). Subsequently, the CPU  11  performs the same processes in steps S 903 , S 904 , S 905 , S 906 , and S 907  as those in steps S 401 , S 404 , S 405 , S 406 , and S 407 , respectively, shown in  FIG. 4  and will be not be described in detail. 
         [0078]    As seen, the second embodiment checks whether the destination email address of an email containing historical information contains the domain name of an email address contained in emails exchanged between multiple users before the email containing the historical information is created. This can prevent the email containing the historical information from being sent to an unintended destination, to which the user does not need to disclose the cited historical information, thereby maintaining confidentiality. Also, the second embodiment collects the domain name of an email address contained in a received email before creating an email containing historical information. Accordingly, when setting a destination email address in the created email containing historical information, the second embodiment can check whether the destination email address contains the domain name. 
         [0079]    The present invention is not limited to the above-mentioned embodiment and various changes, modifications, and like can be made thereto without departing from the spirit and scope of the invention. For example, instead of collecting the domain name of an email address contained in emails exchanged between multiple users and checking whether the destination email address contains the domain name, it is possible to collect the sub-domain name of an email address contained in emails exchanged between multiple users or the entire email address and check whether the destination email address contains the sub-domain name or entire email address. 
         [0080]    As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium having computer readable program code embodied thereon. 
         [0081]    Any combination of one or more computer readable medium may be utilized. The computer readable medium may be a computer readable signal media or a computer readable storage media. A computer readable storage media may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage media may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus or device. 
         [0082]    A computer readable signal media may include a propagated data signal with computer readable program code embodied therein; for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical or any suitable combination thereof. A computer readable signal media may be any computer readable medium that is not a computer readable storage media and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus or device. Program code embodied in a computer readable signal media may be transmitted using any appropriate medium, including but not limited to wireless, wire line, optical fiber cable, RF, etc., or any suitable combination of the foregoing. 
         [0083]    Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). 
         [0084]    Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. 
         [0085]    These computer program instructions may also be stored in a computer readable media that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable media produce an article of manufacture including instructions that implement the function/act specified in the flowchart and/or block diagram block or blocks. 
         [0086]    The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions, which execute on the computer or other programmable apparatus, provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.