PVF Server

The best server written in Java

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Mail Delivery Agent

      This is not a true server (it is not using any port for accepting connections), yet it is a vital part of the e-mail system, as it is implemented on this server. The Mail Delivery Agent is responsible for delivering messages received with various protocols to their destination. The following diagram shows how the MDA operates:

Mail Delivery Agent 

     Email messages sent with various protocols are received by the your server. In the above diagram you can see 3 communication types:
1) A user connects to his/hers local mail server and send a message which is then relayed through the Internet to your server with SMTP.
2) A user connects directly to your server and send a messages (given that the user has a local account), using the SMTP protocol
3) By using the web interface, a user send a message by using the HTTP protocol.

     When the server receives a message, it will be placed in a database. As you can see from the above diagram, there is no direct link between the database and the user folders. This link is made through the Mail Delivery Agent.

     The MDA will handle each request from the database. If the destination is a local user account, the e-mail will be delivered there. If the destination is a remote account (on another server), the MDA will try to deliver it. If the message can not be delivered, the Mail Delivery Agent will place in the database a new message containing an explanation for the delivery.

     A message will fail to reach its intended destination in the following situations:
1) the local user account was deleted before the message can be transferred
2) the remote account does not exist, or does not allow email to be received from the specified source address
3) there is no route to the destination server (the server may not exist, or its server software is not properly configured).

     If the message can not be delivered to a remote address, the Mail Delivery Agent will keep trying for approximately 10 hours. During this time, there will be made 5 attempts with approximately 2 hours of delay. After this time, if the message can not be delivered, there will be a delivery failure notice, that will try to explain what's wrong (it will include, if possible, a full transcript of the communication between your server and the remote server).

     Warning: In order to have a working e-mail system, you must run servers for the following protocols: SMTP or ESMTP, POP3, MDA. For configuring user accounts you must work with the web configuration (either by running the Configuration server or by copying the web interface in your main site).

     For any bug reports don't forget to visit the contact page.

 Recommended Links Recommended Links

 

      If you like PVF Server you should also visit my site http://pvf.cbi.ro.
     Here you can find some more information regarding this project, and also some things about my other projects.

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