December 2003
Intermediate to advanced
408 pages
11h 58m
English
Content preview from sendmail Cookbook
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.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.
Chapter 2. Delivery and Forwarding
Introduction
Inbound mail is either delivered directly to the addressee or relayed to another mail host for delivery. Mail is directly delivered only if it is destined for the local host; mail destined for any other host is relayed. In this chapter, we look at ways to properly configure sendmail to deliver mail locally and forward it to other systems.
Delivery is a multistep process. First, sendmail must process the host portion of the delivery address and recognize that the mail is, in fact, addressed to the local host. If it isn’t addressed to the local host, it is relayed as described in Chapter 3. If it is addressed to the local host, the user portion of the address is processed against the aliases file to determine the proper delivery address. If the aliases file returns an external address, the mail is forwarded to the external host for delivery. If it returns the address of a local mailbox, sendmail checks for a .forward file. If the .forward file exists, the mail is delivered as specified by that file. Otherwise, the mail is delivered to the local mailbox. Figure 2-1 illustrates this delivery flow.[1]
 |
Figure 2-1. The multistep delivery process
sendmail processes each delivery address through the
canonify
ruleset and through
the parse
ruleset—rulesets 3 and 0. Aliasing starts when the result of that process tells sendmail to deliver the mail ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.