December 2003
Beginner
278 pages
10h 47m
English
Content preview from Postfix: The Definitive GuideBecome 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,
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Common Problems
The following error messages in the mail log files indicate host lookup problems:
- mail for
domainloops back to myself This is one of the most common errors related to DNS. It happens when you have configured your Postfix server as an MX host in your DNS server, but you have not told your Postfix server that it is the final destination for the domain. Add the domain in question to the
mydestinationparameter, or configure it as a virtual domain or a relay domain. If your Postfix server is behind a proxy or NAT device, it may not realize that it is an MX host for the domain. In that case, add the proxy device’s IP address toproxy_interfaces. Log entries for this error resemble the following:postfix/qmgr[3981]: 2CC3B229: from=<heloise@ora.com>, \ size=306, nrcpt=1 (queue active) postfix/smtp[3983]: warning: mailer loop: best MX host for \ example.com is local postfix/smtp[3983]: 2CC3B229: to=<abelard@example.com>, \ relay=none, delay=0, status=bounced (mail for example.com \ loops back to myself)- Host found but no data record of requested type
The domain’s DNS configuration has no MX records and there is no A record for the domain itself. You will have to contact an administrator of the domain to fix the problem. For your own domains, be sure they all include MX records pointing to your mail server. Log entries for this error resemble the following:
postfix/qmgr[3818]: D31CD20F: from=<heloise@ora.com>, \ size=312, nrcpt=1 (queue active) postfix/smtp[3824]: D31CD20F: ...
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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.