JP5486452B2 - Web mail server - Google Patents

Description

The present invention relates to Web mail server for providing Web mail service relates.

  As is well-known, e-mail (hereinafter simply referred to as “mail”) users (hereinafter referred to as “mail users”) are not requested to send advertisement emails or emails intended for exploitation of personal information ( (Hereinafter referred to as spam mail) may be sent. Therefore, a general mail user displays a mail list screen as shown in FIG. 10 on the display, and mails that are actually viewed by the “sender” of each mail (and mails that are discarded without browsing). Has been decided.

  However, there is spam mail that spoofs the sender (hereinafter referred to as spoofed mail). Therefore, if you decide to view or discard each email based only on the sender displayed on the email list screen, the email user will view the spoofed email, resulting in the exploitation of personal information. Etc. In addition, the trust of the company / individual who has abused his / her sender name (mail address) for spoofing emails will be lost.

  Therefore, various techniques for determining whether or not the mail is a spoofed mail have been proposed (for example, see Patent Document 1). Each mail user determines whether each mail addressed to himself / herself is a spoofed mail. At present, no technology has been developed that can easily distinguish these.

JP 2009-518751 gazette

Therefore, an object of the present invention is to provide a web mail server that can realize a mail environment in which a mail user can easily identify whether each mail addressed to the mail user is a spoofed mail. It is to provide.

In order to solve the above problems, a web mail server for providing a web mail service to a plurality of users according to the present invention includes a mail storage means for storing an e-mail addressed to each user, and one or more URL storage means for storing the URL of authenticated information prepared as image information for notifying a mail recipient that an e-mail with the mail address as a sender address is not a spoofed mail. And determining means for determining whether or not the e-mail addressed to each user is a spoofed mail, and based on the information stored in the mail storage means and the determination result by the determining means, This is a received mail list Web page that displays the sender name of each received e-mail, and is impersonated by the judging means. For each e-mail that is determined not to be an e-mail, the received e-mail provides a received e-mail list Web page in which the URL stored in the URL storage means is embedded in association with the e-mail source e-mail address. A list Web page providing means.

That is, the Web mail server of the present invention can provide each user with a received mail list Web page in which “authenticated information” is indicated for mail that is surely not spoofed mail in mail addressed to itself. Yes. Therefore, if this Web mail server is used, each user (mail user) can easily identify whether each mail addressed to himself / herself may be a spoofed mail. Can be realized.

Further, when realizing the Web mail server of the present invention, as URL storage means, for each of one or more mail addresses, the mail recipient that the e-mail with the mail address as the sender address is a spoofed mail. A means for storing a warning information URL, which is a URL of warning information prepared as image information for informing the user, is also employed , and the received mail list Web page providing means is determined to be not a spoofed mail by the determining means. For each e-mail, a means for providing a received mail list Web page embedded with a URL embedded with a URL stored in the URL storage means in association with the e-mail source mail address is adopted. I can leave.

  Further, when realizing the Web mail server of the present invention, in order to be able to easily identify whether each mail addressed to itself is a spoofed mail, as a means for providing a received mail list Web page, For each electronic mail that is determined to be a spoofed mail by the determining means, it is desirable to employ a means for providing a received mail list Web page on which warning information indicating that it is a spoofed mail is displayed.

  Further, when realizing the Web mail server of the present invention, it is a mail content Web page in which each user is shown the content of the email selected by each user from the email addressed to each user, and is impersonated by the judging means. For the e-mail that is determined to be an e-mail, an e-mail content Web page providing unit that provides an e-mail content Web page indicating information indicating that it is a spoofed mail can be added. Further, as a mail storage means, a means for storing an electronic mail in which information indicating a determination result by the determination means is included in the mail header is adopted. As the determination means, an email addressed to each user is a spoofed mail. It is also possible to adopt a means for determining whether or not the transmission domain authentication technique is used.

By using the Web mail server of the present invention, it is possible to realize a mail environment in which each mail user can easily distinguish whether or not each mail addressed to himself / herself is a spoofed mail. I can do it.

It is explanatory drawing of the schematic structure and usage pattern of the web mail server which concerns on 1st Embodiment of this invention. It is explanatory drawing of the contract information database with which the Web mail server which concerns on 1st Embodiment is provided. It is explanatory drawing of the image designation | designated information database with which the Web mail server which concerns on 1st Embodiment is provided. It is explanatory drawing of the received mail list Web page which the Web mail server which concerns on 1st Embodiment provides to each user. It is explanatory drawing of the mail content web page which the web mail server which concerns on 1st Embodiment provides to each user. It is a flowchart of the received mail list Web page providing process executed by the Web server unit in the Web mail server according to the first embodiment. It is a flowchart of the header information provision process which the mail management part in the Web mail server which concerns on 1st Embodiment performs. It is a flowchart of the mail provision process which the mail management part in the Web mail server which concerns on 1st Embodiment performs. It is explanatory drawing of the schematic structure and usage pattern of the mail server which concerns on 2nd Embodiment of this invention. It is explanatory drawing of a received mail list screen.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<< First Embodiment >>
First, an outline of the Web mail server 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the following description, the operator of the Web mail server 10 (FIG. 1) is referred to as a server operator. In addition, a person who has a mail account from the server operator is referred to as a user.

  As schematically shown in FIG. 1, the Web mail server 10 is a server (an apparatus / system including one or a plurality of computers) used by being connected to the Internet N, and includes a mail receiving unit 11, A mail management unit 12, a Web server unit 14, and a DB storage unit 15 are provided.

  The DB storage unit 15 is a nonvolatile storage device that stores a contract information database 24 and an image designation information database 25.

  As schematically shown in FIG. 2, the contract information database 24 in the DB storage unit 15 includes “From mail address”, “operation start date”, “spoofing logical expression”, “operation when determination condition is satisfied”. And a database capable of storing a plurality of pieces of contract information consisting of “operation when determination condition is not satisfied”. As schematically shown in FIG. 3, the image designation information database 25 is a database capable of storing a plurality of pieces of image designation information including “FLAG” and “icon URL”.

  The mail receiving unit 11 (FIG. 1) is a unit that receives mail addressed to each user transmitted from a plurality (one in the figure) of the mail distribution system 30 and stores it in the mail storage unit 13 in the mail management unit 12. (One kind of computer). The mail delivery system 30 is a so-called mail server, and the mail storage unit 13 is a non-volatile storage device that functions as a so-called mail box.

  When receiving a mail addressed to a certain user, the mail receiving unit 11 (inside CPU) executes a spoof determination process for the mail according to the spoof determination program 21.

  The spoofing determination process executed by the mail receiving unit 11 determines whether or not the received mail is a spoofing mail (mail spoofing the sender), and displays information indicating the determination result (hereinafter referred to as determination result information). This is a process of adding to the mail header of the received mail (mail stored thereafter in the mail storage unit 13).

This impersonation determination process is a process of performing SPF (Sender Policy Framework) authentication and Sender ID authentication for the received mail. Furthermore, the impersonation determination process is performed by a mail distribution system 30 in which an electronic signature adding program 31 for adding an electronic signature to a mail header of a distribution (transmission) mail is executed. The mail includes an electronic signature (DKIM-signature) header in the mail header. [Email from] is a process of performing DKIM (DomainKeys Identified Mail) authentication. In SPF authentication and DKIM authentication, verification information (public key, etc.) is acquired from the DNS server 40 according to information in the mail header (domain name in the sender address, d tag value in the electronic signature header). Thus, it is a technique for performing authentication of e-mail (determination of whether or not the sender is spoofed).

  The mail management unit 12 prepares the data requested from the Web server unit 14 based on various information in the mail storage unit 13 and the contract information database 24, and performs a process of returning the prepared data to the Web server unit 14 by mail. This unit is executed in accordance with the information providing program 22.

  The Web server unit 14 returns the HTML data and image data requested from each user's PC 50 (Web browser) to each user's PC 50, so that the received mail list Web page and the mail content Web page ( This is a unit for displaying details. The Web server unit 14 is a unit that acquires data necessary for creating HTML data for each Web page from the mail management unit 12 and the image designation information database 25.

  Based on the above, the configuration and operation of the Web mail server 10 according to the present embodiment will be described more specifically below.

  First, the contract information to the contract information database 24 and the image designation information database 25, the setting timing of the image designation information, the meaning of each element information of the contract information and the image designation information, etc. will be described.

  In the Web mail server 10 according to the present embodiment, the received mail list Web page as schematically shown in FIG. 4, that is, an authenticated icon indicating that it is not a spoofed mail or a warning icon indicating that it is a spoofed mail is the sender. The received mail list Web page shown in the column can be provided to each user. Further, the Web mail server 10 displays a mail content Web page as schematically shown in FIG. 5, that is, a message about whether or not the mail being browsed is a spoofed mail (in the figure, the mail being browsed is spoofed). It is also possible to provide each user with a mail content Web page indicating a message indicating that the mail is a mail.

  The contract information database 24 and the image designation information database 25 are “to allow an icon unique to a mail sender to be displayed as an authenticated icon / warning icon” or “to display a service such as an authenticated icon with a server operator. It is a database provided for the purpose of “to be able to perform only for mail from a person who has made a predetermined contract (hereinafter referred to as a contract mail sender)”.

  Specifically, at the time of the above contract with a certain contract mail sender, the display address of the authenticated icon / warning icon, the display start date of the authenticated icon, etc., whether the mail is a spoofed mail. The contents of the process actually performed for the determination are determined. The information (logical formula) representing the predetermined mail address, the predetermined display start date, and the predetermined processing content is the contract information set as the From mail address, the operation start date, and the impersonation determination logical expression, respectively. It is added to the contract information database 24.

  Also, when contracting with a contract email sender, both the authenticated icon and the warning icon are displayed, or only one of them is displayed, or each icon is unique or is shared and authenticated Whether to use an icon / shared warning icon is also determined. Here, in the shared authenticated icon / shared warning icon, the image designation information is set in the image designation information database 25 from the beginning (before the first contract information is added to the contract information database 24). It is an icon. Hereinafter, FLAG in the image designation information for the shared authenticated icon (FLAG associated with the shared certified icon) is referred to as FLAG for the shared authenticated icon, and in the image designation information for the shared warning icon. This FLAG is described as a shared authentication icon FLAG.

When the contract mail sender wishes to display a unique icon as an authenticated icon, a unique FLAG (different FLAG from each existing FLAG) for the icon is determined. Then, image designation information consisting of the FLAG and a URL (the one not including “http: //”) indicating the location where the icon designated by the contract mail sender exists is the image designation information database 25 (FIG. 3). To be added. In addition, in the contract information (FIG. 2) regarding the contract mail sender, information indicating that the FLAG is added to the mail header as “operation when the determination condition is satisfied” (such as “providing FLAG“ ¥ 1000 ””). Is set.

  When the contract mail sender wishes to display the shared authenticated icon as the authenticated icon, the image designation information is not added to the image designation information database 25, and the contract information is displayed as “operation when determination condition is met. "Is set to indicate that the shared authentication icon FLAG is to be added to the mail header. If the sender of the contract email wishes not to display the authenticated icon (if it wishes to display only the warning icon), the “operation when the judgment condition is met” in the contract information is It is set to NULL.

  When displaying a warning icon, information indicating that a common warning icon FLAG is to be added to the mail header is usually set in the contract information as “operation when determination condition is not satisfied”. However, if the contract mail sender wants to display a specific icon as a warning icon, work to assign a unique FLAG to the specific icon, and add image designation information related to the specific icon to the image designation information database 25 And an operation for setting information indicating that a FLAG assigned to the specific icon is added to the mail header as an operation when the determination condition is not satisfied.

  Next, the operation of the Web mail server 10 when the received mail list Web page is provided will be described.

  When a certain user (hereinafter referred to as a user to be processed) starts a web browser of his / her own PC 50 and logs in to the web mail server 10 (web server unit 14), the web server unit 14 Then, the received mail list Web page providing process of the procedure shown in FIG. 6 is started.

  Then, the Web server unit 14 that has started the received mail list Web page providing process first performs a header information acquisition process (step S101).

  This header information acquisition process is a process for acquiring, from the mail management unit 12, the header information of each mail that has arrived at the processing target user. This process repeats the process of issuing a “header information request command for requesting provision of header information of one (first / next) mail reaching the user to be processed” to the mail management unit 12. As a response to the header information request command, the process is terminated when “information indicating that there is no mail that has not been provided with header information” is returned.

  Before describing the contents of the remaining steps of the received mail list Web page providing process, the operation of the mail management unit 12 in response to the header information request command will be described here.

  When the mail management unit 12 receives a header information request command from the Web server unit 14, the mail management unit 12 is configured to execute the header information providing process of the procedure shown in FIG. 7.

  That is, the mail management unit 12 that has received the header information request command first performs a process of reading out the header information of the first / next mail addressed to the processing target user from the mail storage unit 13 (step S201). Although not shown in the flowchart (FIG. 7), the mail management unit 12 determines that the header information request is made after the processing of the header information of all mails addressed to the user to be processed is completed when the process of step S201 fails. When a command is received), “information indicating that there is no mail that has not been provided with header information” is returned to the Web server unit 14 and the header information providing process is terminated.

  The mail management unit 12 that has acquired the header information of a certain mail has contract information (hereinafter referred to as corresponding contract information) including the same From mail address as the From mail address in the header information in the contract information database 24. It is determined whether or not (step S202).

  If the corresponding contract information does not exist in the contract information database 24 (step S202; NO), the mail management unit 12 returns the header information read from the mail storage unit 13 to the web server unit 14 as it is (step S207). Then, the header information providing process is terminated.

  Further, when the corresponding contract information exists (step S202; YES), the mail management unit 12 sets the mail transmission date in the header information to be processed after the operation start date in the corresponding contract information. It is determined whether or not (step S203). If the mail transmission date is not after the operation start date (step S203; NO), the mail management unit 12 returns the header information to the web mail unit as it is (step S207), and then performs header information provision processing. Exit.

  On the other hand, when the mail transmission date is after the operation start date (step S203; NO), the mail management unit 12 uses the determination result information (SPF authentication result, Sender ID authentication result, DKIM authentication result) in the header information, It is determined whether or not an impersonation determination logical expression in the corresponding contract information is established (TRUE) (step S204). Then, if the spoofing determination logical expression is satisfied (step S204; YES), the mail management unit 12 has the contents specified by the operation when the determination condition is satisfied in the corresponding contract information for the header information being processed. An operation is performed (step S205). In other words, if the determination condition in the corresponding contract information is not NULL, the mail management unit 12 adds a FLAG value (such as “¥ 1000”) to the header information being processed in step S205. Do. If the operation when the determination condition is satisfied in the corresponding contract information is NULL, the mail management unit 12 ends the process of step S205 without adding any information to the header information.

  If the spoofing determination logical expression is not satisfied (step S204; NO), the mail management unit 12 performs an operation designated by the operation when the determination condition is not satisfied in the corresponding contract information for the header information being processed. (Step S206).

  Then, the mail management unit 12 that has finished the process of step S205 or S206 returns the header information with the FLAG added (or without the FLAG added) to the Web mail unit 14 (step S207), and then provides the header information. End the process.

  Returning to FIG. 6, the description of the received mail list Web page providing process will be continued.

  The Web mail unit 12 that has acquired the header information of all mails addressed to the user to be processed by performing the header information acquisition process (step S101) is based on the acquired header information group and the information in the image designation information database 25. A process of creating received mail list Web page data (HTML data) capable of displaying the received mail list Web page as shown in FIG. 4 on the Web browser (step S102). More specifically, the Web mail unit 12 reads the icon URL associated with FLAG in each header information (including FLAG) from the image designation information database 25 (see FIG. 4), and reads each icon A process of creating received mail list Web page data in which the URL is embedded in the sender information part of the corresponding mail is performed.

  Then, the Web mail unit 12 returns the generated received mail list Web page data to the PC 50 operated by the user to be processed (step S103), and ends the received mail list Web page providing process.

  Next, the operation of the Web mail server 10 when providing a mail content Web page will be described.

As is clear from FIG. 5, the mail content Web page is a Web page that is displayed when the user to be processed selects an email to browse from the received email list Web page. When receiving an HTTP request for requesting the mail content web page, the web server unit 14 issues a mail request command in a predetermined format, whereby the processing target user requests browsing (all received mails). The mail management unit 12 is requested to output data (provide to the own unit).

  Upon receiving the mail request command, the mail management unit 12 starts the mail providing process of the procedure shown in FIG. 8, and first reads out the mail requested by the command from the mail storage unit 13 (step S301). Thereafter, the mail management unit 12 executes the same content / same procedure (steps S302 to S306) as the header information providing process described above on the header information of the read mail.

  However, when the spoofing determination logical expression is satisfied (step S304; YES), the mail management unit 12 does not perform “operation when the determination condition is satisfied” but uses the header information of the mail read from the mail storage unit 13. Then, a process of adding a predetermined authenticated message presentation required flag is performed (step S305). Further, when the spoofing determination logical expression is not satisfied (step S304; NO), the mail management unit 12 does not perform “operation when the determination condition is not satisfied”, but stores the mail read from the mail storage unit 13. Processing for adding a predetermined warning message presentation flag to the header information (step S306) is performed.

  Then, the mail management unit 12 that has finished the processing of steps S305 and S306 returns the mail added to the authenticated / warning message presentation required flag to the header information to the Web server unit 14, and ends this mail provision processing. .

  The Web server unit 14 that has received the mail returned by the mail management unit 12 in such a procedure sets whether the warning message presentation required flag is set in the header information of the mail or the warning message presentation required flag is set. It is determined whether or not any message presentation required flag is set.

  When the warning message presentation flag is set in the header information of the email from the email management unit 12, the Web server unit 14 indicates that the email being browsed is a spoofed email based on the email. HTML data for displaying the mail content Web page (FIG. 5) indicating the message on the Web browser is prepared and returned to the PC 50 used by the user to be processed.

  Further, when the authenticated message presentation required flag is set in the header information of the email from the email management unit 12, the Web server unit 14 indicates that the email being browsed is not a spoofed email based on the email. HTML data for displaying on the Web browser the mail content Web page showing the message is prepared and returned to the PC 50 used by the user to be processed.

  In addition, when any message presentation flag is not set in the header information of the mail data from the mail management unit 12, the Web server unit 14 displays a normal mail content Web page based on the mail data. HTML data to be displayed on the Web browser is prepared and returned to the PC 50 used by the processing target user.

  As described above, the Web mail server 10 according to the present embodiment allows each user to use each mail addressed to the user (the “From mail address” of any contract mail sender is used as the sender address). ) Has a function of providing a received mail list Web page and a mail content Web page that can easily discriminate whether or not the mail is a spoofed mail. Therefore, if this Web mail server 10 is used, it is possible to realize a mail environment in which each mail user can easily distinguish whether each mail addressed to himself / herself is a spoofed mail.

<< Second Embodiment >>
FIG. 10 shows the configuration and usage of the mail server 20 according to the second embodiment of the present invention.

  As illustrated, the mail server 20 is a server including a mail receiving unit 11, a mail management unit 12, a DB storage unit 15, and a mail server unit 16. The mail server 20 is a modification of the above-described Web mail server 10 into a kind of IMAP compatible mail server. The mail server 20 is a server developed to be used from the PC 50 in which the mail client program 18 (details will be described later) is installed.

  The mail receiving unit 11, the mail management unit 12, and the DB storage unit 15 included in the mail server 20 according to the present embodiment are the same unit as the component having the same name as the Web mail server 10, respectively.

  The mail server unit 16 is a unit that performs the same operation as the above-described Web mail unit 14 according to the mail program 28. Specifically, the mail server unit 16 is a unit that responds to various requests from the mail client program 18 as follows.

  When the mail client program 18 requests the information necessary for displaying the received mail list screen from the mail client program 18, the mail server unit 16 performs the same header information acquisition processing as that performed by the Web server unit 14 to address the processing target user. Get header information of all emails. Next, the mail server unit 16 refers to the image designation information database 25 to perform processing for replacing the FLAG in each header information including the acquired FLAG with the icon URL. Then, the header information in which the FLAG is replaced with the icon URL and the header information not including the FLAG are returned to the mail client program 18.

  The mail server unit 16 issues the same mail request command issued by the Web server unit 14 to the mail management unit 12 when the information necessary for displaying the mail content screen is requested from the mail client program 18. To do. Then, the mail server unit 16 returns the mail returned as a response to the command (the header information may include an authenticated / warning presentation required message) to the mail client program 18 as it is. .

  The mail client program 18 installed in each PC 50 using the mail server 20 is based on the information as described above, the received mail list screen having the same configuration as the received mail list Web page (see FIG. 4), and the mail contents This is a program for displaying a mail content screen having the same configuration as a Web page (see FIG. 5).

  In other words, the mail client program 18 sends a request in a predetermined format to the mail server 20 (mail server unit 16) when an instruction to display the received mail list screen is made, so that the mail client program 18 includes a number of icon URLs. The header information and some header information not including the icon URL are acquired. Then, after acquiring the authenticated / warning icon based on the icon URL in the acquired header information, a received mail list screen having the same configuration as the received mail list Web page is displayed on the display.

In addition, when a mail content screen display instruction operation is performed, the mail client program 18 transmits a request in a predetermined format to the mail server 20 (the mail server unit 16), so that the header information has been authenticated / Get an email or a regular email that contains a warning message. If the message presentation flag is included in the header information of the acquired mail, the mail client program 18 indicates that the mail being browsed is not a spoofed mail or that the mail being browsed is a spoofed mail. Is displayed on the display. Further, when the message presentation required flag is not included in the acquired mail header information, the mail client program 18 displays a normal mail content screen in which such a message is not shown on the display.

  The mail server 20 and the mail client program 18 according to the present embodiment have the above functions. Therefore, if the mail server 20 is used together with the mail client program 18, each user receives each mail addressed to himself / herself (the one using the “From mail address” of any contract mail sender as the sender address). It is possible to construct a network system that can easily distinguish whether it is a spoofed mail.

<Deformation>
The technology according to each of the embodiments described above can be variously modified. For example, the Web mail server 10 can be modified to perform spoofing determination processing only for mail from a contract mail sender. In addition, the Web mail server 10 can be modified to store the mail in which the FLAG or the icon URL is set in the mail header instead of the determination result information in the mail storage unit 13. further,

  In addition, the mail server 20 is modified so that the header information including the determination result information is returned to the mail client program 18, and the mail client program 18 is sent to the mail server 20 based on the determination result information in the header information. By making an inquiry, it can be transformed into a program that obtains an icon to be displayed in the sender column.

  Furthermore, a specific character string can be displayed instead of the authenticated icon / warning icon (that is, image information). In addition, it is natural that the specific configurations of the Web mail server 10 and the mail server 20 and the specific configurations of the contract information database 24 and the image designation information database 25 may be different from those described above. .

DESCRIPTION OF SYMBOLS 10 Web mail server 11 Mail receiving part 12 Mail management part 13 Mail storage part 14 Web server part 15 DB storage part 16 Mail server part 18 Mail client program 20 Mail server 21 Impersonation judgment program 22 Mail information provision program 23 Web mail program 24 Contract Information database 25 Image designation information database 28 Mail program 50 PC

Claims (7)

In a web mail server for providing a web mail service to a plurality of users,
Mail storage means for storing e-mail addressed to each user;
For each of one or more e-mail addresses, the URL of authenticated information prepared as image information for informing the e-mail recipient that an e-mail with the e-mail address as the sender address is not a spoofed e-mail is stored. URL storage means;
Determining means for determining whether or not the e-mail addressed to each user is a spoofed mail;
A received mail list Web page in which, based on the information stored in the mail storage unit and the determination result by the determination unit, each user's sender name of each e-mail addressed to that user is displayed. For each e-mail that has been determined not to be a spoofed mail by the determining means , a received mail list Web page in which the URL stored in the URL storage means is embedded in correspondence with the e-mail source mail address And a received mail list Web page providing means. Judgment condition information that stipulates, for each of a plurality of e-mail addresses, a condition for judging whether or not an e-mail with the e-mail address as a sender address is a spoofed mail by a combination of processing results of a plurality of types of transmission domain authentication processes. Is further provided with determination condition information storage means for storing
The determination means includes
Each time an email to be stored in the mail storage means is received, the plurality of types of transmission domain authentication processes are performed on the received email,
When the received mail list Web page is provided to a certain user by the received mail list Web page providing means, whether or not each e-mail delivered to the user is a spoofed mail is transmitted. Based on the determination condition information stored in the determination condition information storage means in association with the original mail address, a determination is made based on the processing results of the plurality of types of transmission domain authentication processes by the authentication processing means for each e-mail. Web mail server according to claim 1, characterized in that. The received mail list Web page providing means includes:
Wherein for each email that is determined impersonation that the mail by the determination means, to claim 1 or 2, characterized in that to provide a received mail list Web page that warning information is displayed indicating that the spoofing mail The web mail server described. The URL storage means
For each of one or more mail addresses, warning information that is a URL of warning information prepared as image information for notifying a mail recipient that an e-mail with the mail address as a sender address is a spoofed mail Also memorize URL ,
The received mail list Web page providing means includes:
Wherein for each email that it is determined impersonation that the mail by the determination means, received mail list embedded warning information URL that is stored in the URL storage means in association with the sender mail address for each e-mail The web mail server according to any one of claims 1 to 3, wherein a web page is provided. An email content web page that indicates to each user the content of the email selected by each user from among the emails addressed to each user, and for the email that has been determined to be a spoofed email by the determination means, An email content web page providing means for providing an email content web page in which information indicating impersonation email is shown;
The web mail server according to any one of claims 1 to 4, further comprising: The mail storage means
The Web mail server according to any one of claims 1 to 5 , wherein information indicating a determination result by the determination unit is stored in an e-mail including a mail header. The determination means is
The Web mail server according to claim 1, wherein whether or not an electronic mail addressed to each user is a spoofed mail is determined by a transmission domain authentication technique.

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