Operation Using Milter Protocol

Interaction with Postfix system via Milter protocol is organized in the following way:

•Through the transport connection defined by the transport address of drweb-milter (which acts as a Receiver component) Postfix system receives internal commands from Milter API and a message itself. The message is transferred in segments depending on the stage of the mail session (helo, mail from:, rcpt to: etc.). These segments are saved by drweb-milter module to the temporary directory. Through Milter API, drweb-milter transmits instructions to the Postfix system about actions to be applied to the message.

Milter API is a multithreaded library, which allows to process several mail sessions simultaneously. In the interaction solution, described above, Postfix system is a client and drweb-milter is a server, therefore in the mail.cf configuration file of Postfix system it is required to specify address of drweb-milter module, and Postfix system selects the appropriate client address for this connection.

•Through another transport connection, drweb-milter module transfers drweb-maild module commands and waits for response.

In the solution given above, drweb-milter module works as a proxy between the Postfix system interface and drweb-maild module.

Note features of operation through Milter in the synchronous and asynchronous modes.