December 2003
Beginner
278 pages
10h 47m
English
Content preview from Postfix: The Definitive Guide
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The Role of Postfix
Postfix is an MTA and handles the delivery of messages between servers and locally within a system. It does not handle any POP or IMAP communications.
Figure 1-2 illustrates a simple example of message transmission where Postfix handles the responsibilities of the MTA and local delivery. As the MTA, Postfix receives and delivers email messages over the network via the SMTP protocol. For local delivery, the Postfix local delivery agent can deposit messages directly to a message store or hand off a message to a specialized mail delivery agent.
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Figure 1-2. Example network email message delivery
This example shows Postfix as the SMTP server at both ends of the email transaction; however, since Postfix is based on Internet standards, the other email server in this example could easily be any other standards-compliant server. Postfix can communicate with any other server that speaks SMTP (and even some that are not quite fluent). In our example, Heloise wants to send a message to Abelard from her address (heloise@oreilly.com) to his address ( abelard@postfix.org.) Heloise uses her email client to compose her message, which passes it to her MTA (using SMTP). As it happens, her MTA is a Postfix server that allows her to relay messages. After accepting the message from Heloise’s email client, the Postfix server determines where Heloise’s message needs to go, based on Abelard’s ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.