JP5280148B2 - Mail system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mail system, which has high availability, comprising a plurality of mail servers. <P>SOLUTION: The mail system includes a plurality of mail servers and a database shared by the plurality of mail servers. Each of the mail servers performs processing for receiving electronic mail, storing the received electronic mail in the database, accessing the database to retrieve non-delivered electronic mail, and delivering the retrieved electronic mail. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a mail system.

Conventionally, there is a mail system including a plurality of redundant mail servers. In such a mail system, in order to shorten the recovery time when a failure occurs, the standby second mail server monitors the operating first mail server, and a failure occurs in the first mail server. When the second mail server detects this, the second mail server is activated and performs processing to take over the first mail server (Patent Document 1).
JP 2004-104732 A

  However, in the conventional mail system, even if it is attempted to save the recovery time, it takes several hours to take over the data from the first mail server to the second mail server. For example, the second mail server to be replaced takes time to reconstruct the network and check the consistency of the file system. Therefore, there has been a situation in which the e-mail that has already been received by the first mail server is not delivered by the second server until the handover operation is completed.

  As described above, the conventional mail system in which the received e-mail is not delivered within a few hours during the takeover operation is inconvenient for the user, and loses the attractiveness of the e-mail as immediate transmission. .

  The present invention has been made in view of the above-described problems, and provides a highly available mail system in a mail system including a plurality of mail servers.

  (1) The present invention is a mail system including a plurality of mail servers and a database shared by the plurality of mail servers, wherein each of the mail servers includes an accepting unit that accepts an email and an accepted electronic A storage unit that performs processing for storing the mail and the delivery status of the email in the database, and an email that has not been delivered among the emails stored in the database An update unit that performs a process of updating the delivery status of the received e-mail to information indicating that delivery is in progress, and a delivery unit that performs a process of delivering the e-mail that has been updated to information indicating that the delivery status is being delivered Including mail system. The present invention also relates to a program that causes a computer to function as each of the above-described units and a computer-readable information storage medium that stores a program that causes the computer to function as each of the above-described units.

  According to the present invention, even if the service of one mail server is stopped, the operation can be continued from one mail server to the other mail server without taking over work, and the availability is high. A mail system can be provided. That is, according to the present invention, once received e-mail is stored in a database, and one of the plurality of mail servers performs delivery processing. Even if it stops, the other mail server can deliver the electronic mail stored in the database without delay. Furthermore, according to the present invention, the process of delivering an electronic mail based on the delivery status is performed, so that it is possible to avoid duplicate delivery to the same electronic mail.

(2) Further, in the mail system of the present invention, each mail server completes delivery within a predetermined period from the time when the delivery status of the email stored in the database is updated to information indicating that delivery is in progress. A search unit that searches for an e-mail that has not been updated, and the update unit updates the delivery status of the e-mail for which delivery processing has been completed to delivery completion, and delivery of the searched e-mail You may make it perform the process which updates a condition to undelivered.
According to the present invention, even if a mail server that is delivering electronic mail stops, other mail servers can deliver the electronic mail.

  Hereinafter, this embodiment will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

1. Configuration (1) Mail Server The mail system according to this embodiment includes a plurality of redundant mail servers (mail servers S1, S2). FIG. 1 is an example of a functional block diagram of each mail server. Each mail server according to the present embodiment does not need to include all the units illustrated in FIG. 1, and may have a configuration in which some are omitted.

  The storage unit 170 serves as a work area for the processing unit 100 and the like. The storage unit 170 stores a program for causing the computer to function as each unit of the present embodiment (a program for causing the computer to execute processing of each unit). Can be remembered.

  The storage unit 170 is a computer-readable information storage medium such as a RAM (VRAM), an optical disk (CD, DVD), a magneto-optical disk (MO), a magnetic disk, a hard disk, a magnetic tape, or a memory (ROM). In addition, the information storage medium stores programs, data, and the like. That is, the information storage medium stores a program for causing the computer to function as each unit of the present embodiment (a program for causing the computer to execute the processing of each unit).

  The storage unit 170 stores module programs such as a plurality of modules (module 1, module 2, module 3). Note that these modules are executed based on the execution instruction of the module execution unit 117.

  The processing unit 100 performs various processes of the present embodiment based on a program (data) stored in the storage unit 170, and performs various processes using the main storage unit in the storage unit 170 as a work area. The functions of the processing unit 100 can be realized by hardware such as various processors (CPU, DSP, etc.) and programs.

  The processing unit 100 includes a reception unit 111, a storage unit 112, an acquisition unit 113, a determination unit 114, an update unit 115, a search unit 116, a module execution unit 117, a delivery unit 118, a deletion unit 119, and a database control unit 120.

  The accepting unit 111 performs processing for accepting an e-mail. Specifically, the accepting unit 111 performs processing for accepting an e-mail on the network through SMTP (Simple Mail Transfer Protocol). For example, a process of accepting an e-mail transmitted by a MUA (Mail User Agent) of the terminal 20 shown in FIG.

  The storage unit 112 performs processing for storing the received electronic mail, the update identification information MID of the electronic mail, and the delivery status of the electronic mail in a database. For example, when receiving the e-mail, the storage unit 112 assigns unique identification information to the e-mail, and associates the e-mail, the update identification information MID, and the delivery status with the identification information in the database. Process to store. Here, the delivery status is data representing a delivery status such as non-delivery, delivery in progress, delivery completion, delivery error, etc. in numerical values. In addition, the storage unit 112 performs processing for analyzing the received e-mail into an envelope destination, an envelope sender, a message header, a message body, and the like, and each analyzed data is stored in the tables of the databases DB1 and DB2. Perform the process of storing in association.

  The acquisition unit 113 acquires a response result to a request made to the database by the mail server. For example, the acquisition unit 113 acquires a search result for the search request or acquires information on an update result (update success, update failure) for the update request. For example, the acquisition unit 113 requests the database to search for undelivered emails, and acquires the searched emails.

  The determination unit 114 makes a data update request to the database, and determines whether or not the user has an update right based on the result of the update request. The determination unit 114 determines, for example, whether or not the retrieved undelivered electronic mail has a distribution right based on the update result for the distribution status update request. For example, when acquiring a successful update from the database in response to the delivery status update request, the determination unit 114 determines that the delivery right of the retrieved undelivered e-mail is obtained, and from the database in response to the delivery status update request. When the update failure is acquired, it is determined that the user has no delivery right for the searched undelivered e-mail.

  The update unit 115 identifies an email whose delivery status indicates undelivered among the emails stored in the database, and updates the delivery status of the identified email to information indicating that the delivery is in progress. That is, the update unit 115 requests the database to search for undelivered e-mails, obtains search results, identifies e-mails whose delivery status indicates undelivered, and An update request is made for the delivery status of the specified electronic mail to information indicating that delivery is in progress. The update unit 115 updates the update identification information MID at the time of searching for undelivered e-mail (first time point) and the update time (second time point) for requesting update of the delivery status to information indicating that the delivery is in progress. On the condition that the identification information MID matches, an update request is made for the delivery status from undelivered to information indicating that delivery is in progress, and the value (for example, “1”) of the update identification information MID is set to the value at the first time point. An update request is made to a value different from the update identification information MID (for example, “2”).

  When the e-mail delivery process is completed, the update unit 115 updates the delivery status of the e-mail to delivery completed (delivered). The update unit 115 also includes an e-mail that has not been updated to completion of delivery within a predetermined period from when the search unit 116 updates e-mail stored in the database to information indicating that the delivery status is being delivered. If a search is made, the delivery status of the searched e-mail is updated to undelivered.

  The search unit 116 searches for e-mails stored in the database that have not been updated to completion of delivery within a predetermined period from the time when the delivery status is updated to information indicating that delivery is in progress. That is, the search unit 116 within a predetermined period (for example, within 10 minutes) from the time (update date and time) when the delivery status corresponding to the email is updated to information indicating that delivery is being performed among the emails stored in the database. In addition, an electronic mail whose delivery status has not yet been updated to delivery completion is searched.

  The module execution unit 117 performs processing for executing the module 1, the module 2, and the module 3 stored in advance in the storage unit 170. For example, the module 1 execution unit 117a performs a process of executing a module that performs a process of detecting an e-mail virus. The module 2 execution unit 117b performs processing for executing a module for performing processing for registering an electronic mail in the electronic mail storage database. The module 3 execution unit 117c performs a process of executing a module that performs filtering processing on electronic mail based on a predetermined condition. The module execution unit 117 performs a process for executing the modules in accordance with the execution order stored in the databases DB1 and DB2 in advance for each electronic mail stored in the database.

  The delivery unit 118 performs processing for delivering electronic mail stored in the database. For example, the delivery unit 118 performs processing for delivering an electronic mail whose delivery status is updated to information indicating that delivery is in progress. Here, “delivery of e-mail” means processing of delivering received e-mail to other mail servers via SMTP, or local delivery agent for delivery to users having accounts in the same system where the mail server operates. This includes processing for delivery to MDA (Mail Delivery Agent) and delivery to a user who has an account in the same system where the mail server operates without going through MDA. The delivery unit 118 performs processing for delivering an electronic mail when the electronic mail delivery instruction 51 stored in the databases DB1 and DB2 is valid.

  Further, the delivery unit 118 of the present embodiment refers to the address of the delivery destination mail server 53 stored in the database, and performs processing for delivering an email to the delivery destination mail server via the network.

  The deletion unit 119 deletes the electronic mail for which the delivery process has been completed from the database. Specifically, the deletion unit 119 completes all module processing in the module execution unit 117 among the e-mails registered in the databases DB1 and DB2 (all modules 1, 2, and 3 have been executed). The e-mail for which the delivery process of the e-mail for which the delivery instruction is valid is completed, and all the module processing in the module execution unit 117 is completed (the execution of all the modules 1, 2, and 3 is completed). A process of deleting invalid electronic mail from the databases DB1 and DB2 is performed.

  The database control unit 120 performs synchronous replication processing so that the same data is written in the databases DB1 and DB2 of this embodiment. For example, the database control unit 120 performs a process of simultaneously transmitting request data (query) such as storage / update / deletion / reference / search for the database, respectively in the databases DB1 and DB2, and a time lag occurs between the databases DB1 and DB2. And maintain the identity of the data. In addition, when the database control unit 120 detects that a failure has occurred in one database (for example, the database DB1), or detects data inconsistency between the databases DB1 and DB2, the database control unit 120 (for example, the database DB1) The process of separating the database DB1) is performed, and the other database (for example, the database DB2) continues the process of storing / updating / deleting / referring.

(2) Database FIG. 2 shows an example of data stored in the database (database DB1, DB2) of the present embodiment. Here, the database has a function of performing processing such as data management, data storage, deletion, update, reference, and search based on request data (query, command). In each of the databases DB1 and DB2 of the mail system according to the present embodiment, the same data is recorded by the synchronous replication processing of the database control unit 120 in the mail server.

  The e-mail storage area 30 stores e-mail data received by the mail servers S1 and S2. For example, in the e-mail storage area 30, the e-mail received by the mail servers S1 and S2 is associated with unique identification information (ID), the e-mail envelope destination, the e-mail envelope sender, e-mail Contents (header part, body part contents), registration date / time, update date / time, and update identification information (MID) are stored.

  In the module information storage area 40, data of a status 41 of the module 1, a status 42 of the module 2, a status 43 of the module 3, and a progress status 44 are stored. The status 41 of the module 1, the status 42 of the module 2, and the status 43 of the module 3 are execution status data of each module corresponding to the identification information (ID) of the electronic mail. The progress status 44 is module execution status data in accordance with the module execution order.

  In the delivery information storage area 50, a delivery command 51, a delivery status 52, and a delivery destination mail server 53 are stored in association with the identification information (ID) of the electronic mail. The delivery command 51 is data indicating the presence / absence of a delivery command, the delivery status 52 is data indicating a delivery status, and the delivery destination mail server 53 is a delivery destination for the email servers S1 and S2 to deliver an email. This is the mail server address (IP address, mail server name).

2. Processing Method According to this Embodiment (1) Outline of Mail System FIG. 3 shows a network diagram of the mail system according to this embodiment. The present embodiment is a mail system including a plurality of redundant mail servers S1 and S2 and a plurality of redundant databases DB1 and DB2. Here, the mail server is an MTA (Message Transfer Agent), and accepts an e-mail delivered from another mail server via the Internet or an e-mail sent from a LAN (Local Area Network) terminal MUA. Process to deliver.

  The mail servers S1 and S2 of the present embodiment share databases (databases DB1 and DB2) and perform email processing using the same data. That is, in the mail system of the present embodiment, for example, one of the mail servers S1 and S2 receives an e-mail transmitted from the terminal 20 and designated as a destination (transmission destination). Are stored in the databases DB1 and DB2, and one of the mail servers S1 and S2 performs a process of delivering the electronic mail stored in the databases DB1 and DB2 to the mail server of the delivery destination. .

  FIG. 4 shows the flow of a job for electronic mail in the mail system of this embodiment. First, when an electronic mail delivered from another mail server or the like is received by either of the mail servers S1 and S2, it is stored in the databases DB1 and DB2, and one of the mail servers S1 and S2 is When the execution process of module 1 is performed for the electronic mail and the execution process of module 1 is completed, one of the mail servers S1 and S2 performs the execution process of module 2 and the execution process of module 2 is completed. Any one of the mail servers S1 and S2 performs the execution process of the module 3. When the delivery instruction for the electronic mail is valid, either of the mail servers S1 and S2 performs a process of delivering the electronic mail to the delivery destination mail server. When the execution processing of modules 1, 2, and 3 and the delivery processing are all completed, the e-mail is deleted from the database. That is, in the mail system of this embodiment, the email jobs stored in the databases DB1 and DB2 are jobs that execute the module 1 for email, jobs that execute the module 2 for email, and email On the other hand, there are a job for executing the module 3, a job for delivering an electronic mail, and a job for deleting the electronic mail from the database.

  As described above, in the mail system according to the present embodiment, even if one mail server S2 is stopped due to a failure or the like, since the other mail server S1 is operating, the electronic data stored in the databases DB1 and DB2 are stored. E-mail module execution processing and delivery processing can be performed without delay. For example, as shown in FIG. 5, when the mail server S2 is stopped after the completion of the execution of the module 1 in the mail server S2, the mail server S1 executes the module 2 and the module 3 for the electronic mail, and the delivery. Process.

  In the mail system of the present embodiment, the mail servers S1 and S2 may be operated by different devices (hardware), or may be operated by the same device. The database DB1 may be operated by the same device as the mail server S1, or may be operated by a device different from the mail servers S1, S2 and the database DB2. Similarly, the database DB2 may be operated by the same device as the mail server S2, or may be operated by a device different from the mail servers S1, S2 and the database DB1. In addition, the mail servers S1, S2 and the databases DB1, DB2 are connected to the same LAN, and the mail servers S1, S2 have the database names of the databases DB1, DB2 so that data can be transmitted / received to / from the databases DB1, DB2. The database server name (host name), IP address, and port number are stored in the storage unit in advance.

(2) Status Information In this embodiment, status information such as a progress status 44 indicating the module execution progress, statuses 41, 42, 43 of each module, a delivery status 52, etc. is set for each e-mail stored in the database. The mail server according to the present embodiment searches for an unexecuted (unprocessed) job with reference to the status information, and performs a process of executing the searched job.

  FIG. 6A shows a list of progress status 44. First, when the modules 1, 2, and 3 are not executed for the e-mail, that is, when none of the modules 1, 2, and 3 is executed, the value of the progress status 44 is “1”. "Is set. Then, regarding the e-mail, in the situation before the execution of the module 1 is completed and the execution of the module 2 is completed, the value of the progress status 44 is set to “2”. Then, regarding the e-mail, in the situation before the execution of the modules 1 and 2 is completed and the execution of the module 3 is completed, the value of the progress status 44 is set to “3”. If the execution of modules 1, 2, and 3 is completed for the electronic mail, the value of the progress status 44 is set to “4”.

  FIG. 6B shows a list of statuses 41, 42, and 43 of modules 1, 2, and 3. For example, when the module 1 has not been executed for the e-mail, the value of the status 41 of the module 1 is set to “1”. When the module 1 is being executed for the electronic mail, the value of the status 41 of the module 1 is set to “2”. When the execution of the module 1 is completed, the value of the status 41 of the module 1 is set to “3”. When the execution of the module 1 ends with an error, the value of the status 41 of the module 1 is set to “4”. The value of the status 42 of the module 2 and the value of the status 43 of the module 3 are set in accordance with the execution status in the same manner as the status 41 of the module 1.

  FIG. 6C shows a list of delivery status 52. For example, if the delivery status for the electronic mail is not delivered, the value of the delivery status 52 is set to “1”. When the delivery status is “delivery” for the electronic mail, the value of the delivery status 52 is set to “2”. Then, when the delivery status of the electronic mail is completed, the value of the delivery status 52 is set to “3”. If the delivery process ends with an error, the value of the delivery status 52 is set to “4”.

(3) Receiving process As shown in FIG. 3, the mail servers S1 and S2 of the present embodiment are transmitted from an email delivered from another mail server via the Internet or an MUA of the terminal 20 via SMTP. The electronic mail is received, and the received electronic mail is stored in the databases DB1 and DB2. In other words, in the present embodiment, the mail servers S1 and S2 perform processing for spooling the received electronic mail to the databases DB1 and DB2 shared by the mail servers S1 and S2.

  Also, as shown in FIG. 3, the DNS record of the DNS (Domain Name System) of the mail system of this embodiment is a record that defines the mail server name of the mail server S1 in association with the same domain of the mail address. And a record defining the mail server name of the mail server S2. At that time, the priorities (preference values) of the MX records of the mail server S1 and the mail server S2 may be set to be the same. In this way, each of the mail servers S1 and S2 can accept e-mails almost evenly.

  In the present embodiment, when the e-mails received by the mail servers S1 and S2 are stored in the databases DB1 and DB2, the progress status 44 is set to “1” (not executed), and e-mail identification information ( ID) and stored in the databases DB1 and DB2, and the statuses 41, 42, and 43 of the modules 1, 2, and 3 are set to “1” (not executed) to correspond to the identification information (ID) of the e-mail. Then, the data is stored in the databases DB1 and DB2, the delivery status 52 is set to “1” (not delivered), and stored in the databases DB1 and DB2 in association with the identification information (ID) of the e-mail.

(4) Processing for executing modules The mail servers S1 and S2 of the present embodiment perform processing for executing a plurality of modules for electronic mail. The plurality of modules are, for example, a virus detection module that detects a virus, a module that accumulates e-mails in an external storage area, a module that performs e-mail filtering, and the like.

  In this embodiment, the execution order of these modules is stored in advance in a database in association with the modules. For example, a virus detection module that detects a virus is first executed as module 1, a module that accumulates e-mails in the external storage area is secondly executed as module 2, and a module that performs e-mail filtering is designated as module 3. The execution order of the third execution is stored in the database so that each mail server can share it.

  In this embodiment, the progress status 44 and the statuses 41, 42, and 43 of the modules 1, 2, and 3 are referred to, and control is performed so that each module is executed in the module execution order for each e-mail.

  For example, the execution processing of each module with respect to the electronic mail A in which the progress status 44 is “1” (not executed) and the statuses 41, 42, and 43 of each module are “1” (not executed) will be described.

  First, the mail servers S1 and S2 search for an email whose progress status 44 is “1” (not executed) (an email whose status 41 of the module 1 is “1” (not executed)). For example, it is assumed that the mail server S1 searches the electronic mail A before the mail server S2. Then, the mail server S1 performs a process of executing the module 1 for the email A. In this embodiment, the mail server S1 updates the status 41 of the module 1 of the email A to “2” (running) before executing the module 1 for the email A, and then the module for the email A. 1 is executed. As described above, the reason why the status 41 of the module 1 is updated before the execution of the module 1 is that the module 1 of the other mail server S2 searches the electronic mail A during the execution of the module 1 of the one mail server S1. This is in order to avoid executing. When the execution of the module 1 is completed in the mail server S1, the mail server S1 updates the status 41 of the module 1 for the electronic mail A to “3” (execution complete), and sets the progress status 44 to “2” (execution complete). Update to Module 1 execution complete).

  Then, the mail servers S1 and S2 search for an e-mail whose progress status 44 is “2” (execution completion of module 1) and whose status 42 of module 2 is “1” (not executed). For example, assume that the mail server S1 searches for the email A before the mail server S2. Then, the mail server S1 performs a process of executing the module 2 for the email A. At that time, before executing the module 2 for the email A, the mail server S1 updates the status 42 of the module 2 of the email A to “2” (running), and then the module 2 for the email A. Execute. When the execution of the module 2 is completed in the mail server S1, the mail server S1 updates the status 42 of the module 2 for the electronic mail A to “3” (execution complete), and the progress status 44 is “3”. Update to (complete execution of module 2).

  The mail servers S1 and S2 search for an e-mail whose progress status 44 is “3” (execution completion of module 2) and whose status 43 of the module 3 is “1” (not executed). For example, assume that the mail server S1 searches for the email A before the mail server S2. Then, the mail server S1 performs a process of executing the module 3 for the electronic mail A. At that time, before the mail server S1 executes the module 3 for the email A, the status 43 of the module 3 of the email A is updated to “2” (running). Execute. When the execution of the module 3 is completed in the mail server S1, the mail server S1 updates the status 43 of the module 3 for the electronic mail A to “3” (execution completed), and sets the progress status 44 to “4”. Update to (completion of execution of module 3).

  As described above, in the present embodiment, by referring to the progress status 44 and the statuses 41, 42, and 43 of the modules 1, 2, and 3, processing for executing the modules 1, 2, and 3 for each email is performed. .

  In this embodiment, in order to avoid duplication processing, one of the plurality of mail servers S1 and S2 performs the execution process of the module 1, and the plurality of mail servers S1 and S2 Among these, any one mail server performs the execution process of the module 2, and one of the plurality of mail servers S1 and S2 performs the execution process of the module 3. In the present embodiment, the mail server that first searches for an unexecuted module acquires the module execution right and causes the module to be executed.

  As described above, according to the mail system of the present embodiment, the mail server (for example, the mail server S1) that accepts the e-mail can acquire the right to execute each module of the e-mail and execute each module. Then, a mail server (for example, mail server S2) different from the mail server (for example, mail server S1) that accepted the electronic mail can acquire the right to execute each module of the electronic mail and execute each module. Therefore, even if one mail server is stopped, the other mail server can continue the execution process of each module for the e-mail, and an available mail system can be provided. .

(5) Delivery processing In this embodiment, the mail servers S1 and S2 refer to the delivery instructions 51 stored in the databases DB1 and DB2, and the emails for which the delivery instructions 51 are set to be valid Process to deliver. Note that the validity / invalidity of the delivery instruction 51 of this embodiment may be set as an initial value, or may be set during execution of at least one of the modules 1, 2, and 3. Also good. For example, in the processing of the module 1 for detecting a virus, the delivery command 51 is set to be valid for an e-mail that is determined to have no virus, and the delivery command 51 is set to be invalid for an e-mail that is determined to have a virus. . The validity / invalidity of the delivery command is set using, for example, a delivery flag. Specifically, the delivery flag is set to true when the delivery command is valid, and the delivery flag is set to false when the delivery command is invalid.

  In this embodiment, the mail servers S1 and S2 search for an e-mail in which the delivery status 52 is “1” (not delivered) and the delivery instruction 51 is set to be valid, Processing to deliver mail to the destination mail server.

  For example, a description will be given of a delivery process for the electronic mail A in which the delivery command 51 is set to be valid and the delivery status 52 is “1” (not delivered).

  First, the mail servers S1 and S2 search for e-mails for which the delivery command 51 is valid and the delivery status 52 is “1” (not delivered). For example, it is assumed that the mail server S1 searches the electronic mail A before the mail server S2. Then, the mail server S1 performs processing for delivering the electronic mail A to the delivery destination mail server. In the present embodiment, the mail server S1 updates the delivery status 52 of the email A to “2” (delivering) before starting delivery processing for the email A, and then performs delivery processing for the email A. Let it begin. As described above, the reason for updating the delivery status 52 before starting the delivery process is that the other mail server S2 searches the electronic mail A for delivery during delivery of one mail server S1, as in the case of execution of the module. This is to avoid performing the processing. When the mail server S1 completes the delivery process, the mail server S1 updates the delivery status 52 of the electronic mail A to “3” (delivery completed).

  In the present embodiment, in order to avoid duplication processing, one of the plurality of mail servers S1 and S2 is controlled to perform delivery processing. For example, in this embodiment, a mail server that has a valid delivery command and searches for an undelivered e-mail first acquires the delivery right and performs the e-mail delivery process.

  As described above, according to the mail system of the present embodiment, the mail server (for example, the mail server S1) that accepts the electronic mail can acquire the right to deliver the electronic mail and perform the delivery processing. A mail server (for example, mail server S2) different from the mail server that has received the mail (for example, mail server S1) can acquire the right to deliver the electronic mail and perform the delivery process. Therefore, even if one mail server is stopped, the other mail server can continue the delivery process, and an available mail system can be provided.

(6) Method for avoiding duplication processing In this embodiment, in order to avoid duplication processing, the mail server that searches for an unexecuted module first among the plurality of mail servers S1 and S2 The execution right is acquired, the module is executed, and the mail server that has the delivery command valid and searches for undelivered e-mail first among the plurality of mail servers S1, S2 is delivered. The right is acquired and the delivery process of the e-mail is performed.

  More specifically, in this embodiment, by referring to the update identification information MID, the mail server having the right to execute the module or the mail server having the delivery right is determined from among the plurality of mail servers S1 and S2. The

  FIG. 7A shows a method for determining whether or not each mail server has a delivery right for the electronic mail A in which the delivery command 51 is valid and the delivery status 52 is “1” (not delivered). It is a figure for demonstrating. For example, when the mail server S1 searches for an email A whose delivery command 51 is valid and the delivery status 52 is “1” (not delivered), the update is performed at the time when the email A is searched (time T1). The identification information MID is acquired.

  Then, the mail server S1 accesses the databases DB1 and DB2 to request an update of the delivery status 52 from “1” (not delivered) to “2” (delivered) (at time T3), during search (T1). The update identification information MID of the e-mail A is searched (time T1) on condition that the update identification information MID at the time) matches the update identification information MID at the time of the update request of the delivery status 52 (time T3). Update identification information MID (for example, MID = 2) different from the update identification information MID (MID = 1), and update the delivery status 52 from “1” (not delivered) to “2” (delivered) A request to make is made to the databases DB1 and DB2.

  If the update identification information MID at the time of search (time T1) matches the update identification information MID at the time of the update request of the delivery status 52 (time T3), the update identification information MID in the databases DB1 and DB2 The update process of the delivery status 52 is successful. The mail server S1 determines that it has a delivery right when it acquires update success information from the databases DB1 and DB2, and performs processing for delivering the email A.

  On the other hand, if the update identification information MID at the time of retrieval (time T1) and the update identification information MID at the time of the update request of the delivery status 52 (time T3) do not match, the update identification information MID and The update process of the delivery status 52 fails. When the mail server S1 acquires update failure (error) information from the databases DB1 and DB2, the mail server S1 determines that the mail server S1 does not have a delivery right, and controls not to perform the delivery process of the email A.

  In the example of FIG. 7A, the mail server S1 updates the update identification information MID (MID = 1) at the time of search (time T1) and the update identification information MID (MID at the time of the update request of the delivery status 52 (time T3). = 1), the update identification information MID and the delivery status 52 are successfully updated, and the mail delivery server S1 performs a process of starting the delivery process for the electronic mail A.

  Further, considering from the viewpoint of the mail server S2, the mail server S2 is an e-mail A in which the delivery command 51 is valid and the delivery status 52 is “1” (not delivered) at the time T2 immediately after the time T1. When the e-mail A is searched, the update identification information MID is acquired at the time when the e-mail A is searched (time T2).

  The mail server S2 accesses the databases DB1 and DB2 and requests the update of the delivery status 52 from “1” (not delivered) to “2” (delivered) (at time T4), at the time of search (T2). The update identification information MID of the e-mail A is searched (time T2) on condition that the update identification information MID at the time) matches the update identification information MID at the time of the update request of the delivery status 52 (time T4). Update identification information MID (for example, MID = 2) different from the update identification information MID (MID = 1), and update the delivery status 52 from “1” (not delivered) to “2” (delivered) A request to make is made to the databases DB1 and DB2.

  However, here, in the databases DB1 and DB2, the value of the update identification information MID is updated from 1 to 2 by the mail server S1 at the time T3, so that the update identification at the time when the e-mail A is searched (time T2). The information MID (MID = 1) and the update identification information MID (MID = 2) at the time of status update request (time T4) do not match, and the mail server S2 acquires update failure information from the databases DB1 and DB2. When the mail server S2 acquires the update failure information, the mail server S2 determines that the electronic mail A does not have a delivery right, and controls not to perform the delivery process.

  As described above, in this embodiment, since the update identification information MID is updated simultaneously with the update of the delivery status 52, for example, the delivery to the mail server S1 with a slight difference in the other mail server S2. It is possible to avoid duplication processing.

  Further, as shown in FIG. 7B, the mail server S1 performs processing for updating the value of the delivery status 52 using the update identification information MID even when the delivery processing of the email A is completed. For example, the mail server S1 requests the databases DB1 and DB2 to update the delivery status 52 from “2” (delivering) to “3” (delivery completed).

  In such a case, the update identification information MID at the time when the e-mail A was updated immediately before (T3 time) and the time when the update status 52 is requested to be updated from “2” (delivery) to “3” (delivery completed) (T7). Update identification information MID of e-mail A is different from the update identification information MID (MID = 2) at the time of the last update (time T3) on condition that the update identification information MID at the time) matches. While updating to MID (for example, MID = 3), a request to update the delivery status 52 from “2” (during delivery) to “3” (delivery completed) is made to the databases DB1 and DB2.

  In the example of FIG. 7B, the mail server S1 matches the update identification information MID at the time T3 with the update identification information MID at the time of the update request (time T7) (MID = 2). The update identification information MID of the mail A is updated to update identification information MID (for example, MID = 3) different from the update identification information MID (MID = 2) at the time of the previous update (at time T3), and the delivery status 52 is changed. , “2” (during delivery) can be updated to “3” (delivery completed).

  In this way, even when a plurality of mail servers S1, S2 share the same database DB1, DB2, problems such as deadlock can be avoided.

  In this embodiment, every time not only the delivery status 52 but also the progress status 44 and the statuses 41, 42, 43 of the modules 1, 2, 3 are updated, the update identification information MID is used to update the mail server S1, It may be determined whether S2 has an update right (module execution right, delivery right), and the mail system as a whole may be controlled so as to avoid duplication processing or cause contradiction.

(7) Error Search In the present embodiment, when the execution of the module 1 is not completed within a predetermined period from the time when the status 41 of the module 1 is updated to “2” (running), that is, within the predetermined period. When the status 41 of the module 1 has not been updated to “3” (execution completion), processing for updating the status 41 of the module 1 to “1” (not executed) is performed. Similarly, for the status 42 of the module 2 and the status 43 of the module 3, the module status is “3” (execution completed) within a predetermined period from the time when the module status is updated to “2” (under execution). If it has not been updated, the module status is updated to “1” (not executed). Further, when the delivery process is not completed within a predetermined period from when the delivery status 52 is updated to “2” (delivering), that is, from when the delivery status 52 is updated to “2” (delivery). If the delivery status 52 has not been updated to “3” (delivery completed) within a predetermined period, processing for updating the delivery status 52 to “1” (not delivered) is performed.

  For example, as shown in FIG. 7C, the delivery status 52 is updated to “3” (delivery completed) within a predetermined period (10 minutes) from the time when the delivery status 52 is updated to “2” (delivery). The mail servers S1 and S2 search for e-mails that are not executed. In other words, the mail servers S1 and S2 still have the delivery status 52 of “2” in the e-mail stored in the database even after a predetermined period has elapsed since the delivery status 52 was updated to “2” (delivering). Search for e-mails that are "" (delivering). Then, for example, within a predetermined period from when the mail server S2 updates the delivery status 52 to “2” (during delivery) before the mail server S1, the delivery status 52 becomes “3” (delivery completed). When the e-mail A that has not been updated is searched, the mail server S2 performs a process of updating the delivery status 52 of the e-mail A to “1” (not delivered). In this way, even if the mail server S1 stops in the middle of delivery of the email A, the email A is again searched as an undelivered email and given an opportunity to be delivered. It will be.

(8) Deletion Processing In this embodiment, the status 41, 42, 43 of each module is “3” (execution completed), the delivery command 51 is valid, and the delivery status 52 is “3” (delivery completed). A certain e-mail and an e-mail in which the statuses 41, 42, and 43 of each module are “3” (execution completed) and the delivery command 51 is invalid are searched, and the searched e-mails are stored in the databases DB1 and DB2. Process to delete from. That is, since all jobs for the e-mail searched for deletion have been completed, the e-mails from the databases DB1 and DB2, and the statuses 41, 42, 43, the progress status 44, and the delivery of each module corresponding to the e-mail The status 52 is deleted.

3. Method of sharing data between mail servers In this embodiment, since emails are stored in the databases DB1 and DB2, information can be shared between the mail servers S1 and S2 without rewriting header information. For example, normally, when delivering and receiving e-mail between mail servers, when sharing specific information between mail servers, it was necessary to record the specific information in the header portion of the e-mail . However, according to the mail system of this embodiment, when specific information is shared in the mail servers S1 and S2, the specific information only needs to be stored in the databases DB1 and DB2. The specific information can be shared between the mail servers S1 and S2 without recording the information.

4). Flowchart The flow of processing of the mail servers S1 and S2 of this embodiment will be described with reference to FIG. First, an unexecuted job is searched (step S1). For example, for each of one or a plurality of electronic mails stored in the database, an electronic mail having an unexecuted job is searched based on the status information of each electronic mail and a delivery command. For example, a job is a process for executing a module for an e-mail, a process for delivering an e-mail, a process for deleting an e-mail from the databases DB1 and DB2, and the like.

  More specifically, an e-mail whose progress status 44 is “1” (modules 1, 2, 3 are not executed) is searched as a job of module 1 is not executed. In addition, an e-mail whose progress status 44 is “2” (execution completion of module 1) and status 2 of module 2 is “1” (not executed) is searched for the job of module 2 not being executed. Is done. In addition, an e-mail whose progress status 44 is “3” (execution completion of module 2) and status 43 of module 3 is “1” (not executed) is searched on the assumption that the job of module 3 is not executed. Is done.

  If the delivery command 51 is valid and the delivery status 52 is “1” (not delivered), the e-mail delivery job is retrieved as not executed. In this embodiment, an e-mail in which the delivery command 51 is valid and the delivery status 52 is “1” (undelivered) regardless of the values of the progress status 44 and the module statuses 41, 42, and 43. , The delivery is retrieved as unexecuted.

  Then, it is determined whether or not there is an unexecuted job (step S2). If it is determined that there is an unexecuted job (Yes in step S2), the process proceeds to the next process. On the other hand, if it is determined that there is no unexecuted job (No in step S2), the process ends.

  Then, the searched job is executed (step S3). For example, when the e-mail A of the unexecuted module 1 is searched, a process for executing the module 1 is performed for the e-mail A. Then, it is determined whether or not all the searched jobs have been completed (step S4). If all the searched jobs have been completed (Yes in step S4), the process is terminated. If all the searched jobs have not ended (No in step S4), the process returns to step S3 to execute a process for executing a job that has not ended. In the present embodiment, after the process is completed, the process returns to step S1 again, and the process is permanently repeated.

5. Application Examples (1) As an application example of the mail system of the present embodiment, for example, the mail servers S1 and S2 store received e-mails in the databases DB1 and DB2, and the mail servers S1 and S2 are stored in the databases DB1 and DB2. You may make it perform the process which acquires the stored email and delivers it. In other words, each mail server obtains e-mails stored in the databases DB1 and DB2 by accepting e-mails, executing the process of storing the received e-mails in the databases DB1 and DB2, without executing modules. Perform delivery processing. In such a case, the e-mail A stored in one mail server S1 can be acquired by the other mail server S2 and delivered to the e-mail A, so that one mail server S1 is temporarily stopped. Even in this case, the mail server S2 can deliver the electronic mail accepted by the mail server S1, and the whole mail system can prevent the acceptance of the electronic mail and the delivery service.

  (2) In the mail system according to the present embodiment, an e-mail retrieved as an undelivered e-mail is designated with an envelope destination that is the same as an e-mail envelope destination that is delivered by another mail server. If the received e-mail is, the searched e-mail may not be delivered.

  For example, the mail server S1 performs a process of delivering an email attached with an encrypted file (hereinafter referred to as “first email”) based on the destination of the envelope of the first email, The mail server S2 is an email for notifying the decryption password of the encrypted file attached to the first email that is the destination of the envelope of the first email and the same envelope (hereinafter referred to as the email address). In some cases, a process of delivering “second e-mail”) is performed.

  In this case, since the mail server S1 requires processing time to encrypt the attached file, the mail server S2 completes the delivery of the second e-mail before the mail server S1 completes the delivery of the first e-mail. May end up. That is, when a plurality of electronic mails are delivered to the same destination, the delivery start order and the delivery completion order may be different. Thus, if the delivery start order and the delivery completion order are different, for example, a recipient who should originally receive the first e-mail before the second e-mail receives the second e-mail. After that, there is a possibility that the first e-mail will be received and confused.

  Therefore, when searching for undelivered e-mails, the mail servers S1 and S2 of the mail system according to the present embodiment search for other e-mails having the same envelope destination as that of the e-mail envelope. If the delivery status 52 of the other retrieved electronic mail is “2” (delivering), control is performed so that undelivered electronic mail is not delivered.

  For example, when the mail server S2 searches for an undelivered second e-mail, the e-mail server S2 searches for an e-mail that has the same envelope destination as the second e-mail envelope destination, Suppose an email is retrieved. Then, when the mail server S2 determines that the delivery status 52 of the first email is “2” (delivery) by referring to the delivery status 52 of the retrieved first email, the second Control not to deliver e-mail. That is, while the delivery status 52 of the second e-mail remains “1” (undelivered), the second e-mail delivery job is ignored, and the process proceeds to the execution processing of another searched job. The ignored second electronic mail has a delivery status 52 of “1” (undelivered) and is a job search target of the mail servers S1 and S2, so the opportunity to be delivered is not lost.

  In this way, for example, even if the mail server S1 takes a processing time to encrypt the attached file, the mail server S2 is able to send the second electronic mail while the mail server S1 is delivering the first electronic mail. Since the mail delivery process is controlled not to be performed, the second electronic mail is delivered after the first electronic mail is delivered. That is, even when a plurality of electronic mails are delivered to the same destination, the delivery start order and the delivery completion order can be set in the same order.

  (3) The mail system of the present embodiment controls the delivery of an email envelope destination domain of an email delivered by another mail server and an email in which the same envelope destination domain is designated. You may do it. In this way, for example, as in the above application example (2), when a plurality of electronic mails are delivered to the same domain, the problem that the delivery start order is different from the delivery completion order is solved. In addition, even if there is a problem that delivery to a domain slows down, not all mail servers deliver to that domain, so the impact on the entire mail system can be reduced. it can.

  That is, when the mail servers S1 and S2 of the mail system according to the present embodiment search for an undelivered electronic mail, an envelope destination having the same domain as the destination domain of the envelope of the electronic mail is designated. When another electronic mail is searched and the delivery status 52 of the other searched electronic mail is “2” (delivering), control is performed so that undelivered electronic mail is not delivered.

  For example, when the mail server S2 searches for an undelivered third e-mail, the e-mail server S2 searches for an e-mail in which an envelope destination having the same domain as the envelope destination domain of the third e-mail is specified. Assume that the first e-mail is retrieved. When the mail server S2 determines that the delivery status 52 of the first email is “2” (delivery) by referring to the delivery status 52 of the retrieved first email, Control not to deliver e-mail. That is, while the third electronic mail delivery status 52 remains “1” (undelivered), the third electronic mail delivery job is ignored, and the process proceeds to the execution processing of another searched job. Since the ignored third electronic mail has a delivery status 52 of “1” (not delivered) and is a job search target of the mail servers S1 and S2, the opportunity for delivery is not lost.

  (4) In the mail system of the present embodiment, control is performed so as to perform delivery processing for an electronic mail for which the delivery command is set to be valid, but it is stored in the databases DB1 and DB2 regardless of the delivery command. All e-mails may be delivered.

  (5) In the mail system of the present embodiment, the mail server that first searched for an email whose module status 41, 42, 43 is “4” (execution error) among the mail servers S1, S2 is searched. The execution of the module may be performed again on the executed execution error e-mail.

  Further, in the mail system of the present embodiment, the mail server that first searched for the e-mail having the delivery status 52 of “4” (delivery error) among the mail servers S1 and S2 is the electronic mail of the searched delivery error. The delivery process may be performed again on the mail.

The mail server of the mail system of this embodiment. The database of the mail system of this embodiment. The network diagram of the mail system of this embodiment. FIG. 6 is a diagram illustrating an example of an e-mail job according to the present embodiment. FIG. 6 is a diagram illustrating an example of an e-mail job according to the present embodiment. Explanatory drawing of the status information of this embodiment. The figure for demonstrating the process using the update identification information of this embodiment. The figure for demonstrating the process using the update identification information of this embodiment. The figure for detecting the error of this embodiment. The flowchart of the mail server of this embodiment.

Explanation of symbols

S1, S2 mail server, DB1, DB2 database, 20, 21 terminal,
30 Email storage area,
40 Module information storage area,
41 Module 1 status, 42 Module 2 status,
43 Module 3 status, 44 progress status,
50 delivery information storage area, 51 delivery instruction,
52 delivery status, 53 delivery mail server,
100 processing unit, 111 receiving unit, 112 storage unit, 113 acquiring unit,
114 determination unit, 115 update unit, 116 search unit, 117 module execution unit,
117a module 1 execution unit, 117b module 2 execution unit,
117c module 3 execution unit, 118 delivery unit, 119 deletion unit,
120 database control unit, 170 storage unit

Claims (3)

A mail system including a plurality of mail servers and a database shared by the plurality of mail servers,
Each of the mail servers
A reception unit for receiving e-mail;
A storage unit that performs processing for storing the received e-mail and the delivery status of the e-mail in the database;
An update unit that performs processing for identifying an email whose delivery status is undelivered among emails stored in the database, and updating the delivery status of the specified email to information indicating that delivery is in progress;
A delivery unit that performs a process of delivering the electronic mail whose delivery status is updated to information indicating that delivery is in progress ;
A search unit that searches for e-mails that have not been updated to completion of delivery within a predetermined period from the time when the delivery status is updated to information indicating that delivery is being performed, among the e-mails stored in the database,
The update unit
Processing to update the delivery status of emails that have completed delivery processing to delivery completion,
A mail system that performs a process of updating the delivery status of the searched e-mail to undelivered. In claim 1,
  Each of the mail servers performs a process of delivering the e-mail after performing a module execution process on the e-mail,
Module execution that performs processing to identify an email whose module execution status is not executed from among emails stored in the database and update the module execution status of the specified email to information indicating that it is being executed A status update department;
  A module for executing a predetermined module process on the e-mail whose module execution status is updated to information indicating that the module execution status is being executed before the delivery unit performs the process of delivering the e-mail.
A module execution unit,
  A module unexecuted mail search unit that searches for e-mails that have not been updated to completion within a predetermined period from when the module execution status is updated to information indicating that the module execution status is being executed, among the e-mails stored in the database; Further including
  The module execution status update unit
  A process of updating the module execution status of an email for which execution of a predetermined module process has been completed to execution completion;
  And a process of updating the module execution status of the electronic mail searched by the module non-executed mail search unit to unexecuted. In claim 2 ,
The storage unit
A process of storing the received delivery instruction of the e-mail in the database;
The module execution unit
Depending on the execution result of the predetermined module processing for the email, the delivery command for the email is set to be valid,
The update unit
Information indicating that the delivery command is valid and the delivery status is undelivered among the emails stored in the database, and the delivery status of the identified email is indicated as being delivered A mail system characterized by performing a process of updating to

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