Solved

Mail server spitting back Email

Posted on 2000-03-06
3
258 Views
Last Modified: 2013-12-16
I am running Slackware with sendmail running as pop3 and smtp server

When people try to send mail to the server

someone@mydomain.com

Mail servers are spitting it back saying that it is looping back to them, and maybe its an MX problem

This server was working fine and I don't know what happened to it??

Any help is greatly appreciated
0
Comment
Question by:eric007
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 3

Expert Comment

by:RobWMartin
ID: 2589147
Do you administrate the DNS that advertises your mail server?  If so, can you post the relevant parts of your zone file, esp. the MX record and anything mentioning mydomain.com.  Also, can we see the exact error message?

Thx
0
 
LVL 40

Accepted Solution

by:
jlevie earned 100 total points
ID: 2589521
There could be a DNS problem, but more likely the problem is the sendmail config. The Sendmail FAQ says:

I'm getting these error messages:

        553 MX list for domain.net points back to relay.domain.net
        554 <user@domain.net>... Local configuration error

How can I solve this problem?

You have asked mail to the domain (e.g., domain.net) to be forwarded to a specific host (in this case, relay.domain.net) by using an MX record, but
the relay machine doesn't recognize itself as domain.net. Add domain.net to /etc/sendmail.cw (if you are using FEATURE(use_cw_file)) or add "Cw
domain.net" to your configuration file.

IMPORTANT: When making changes to your configuration file, be sure you kill and restart the sendmail daemon (for ANY change in the
configuration, not just this one):
0
 
LVL 40

Expert Comment

by:jlevie
ID: 2589539
Oh yeah, if it's a DNS problem the usual cause, per the sendmail FAQ (http://www.sendmail.org/faq/), is:

Wildcard MX records have lots of semantic "gotcha"s. For example, they will match a host "unknown.your.domain" -- if you don't explicitly test for
unknown hosts in your domain, you will get "MX list for hostname points back to hostname" or "config error: mail loops back to myself".

See RFCs 1535, 1536, and 1912 (updates RFC 1537) for more detail and other related (or common) problems. See also _DNS and BIND_ by
Albitz and Liu.

They can also cause your system to add your domain to outgoing FQDNs in a desperate attempt to get the mail to where it's supposed to go, but
because *.your.domain is valid due to the wildcard MX, delivery to not.real.domain.your.domain will get dumped on you, and you may even find
yourself in a loop as the domain keeps getting tacked on time after time after time (the "config error: mail loops back to myself" problem).

Wildcard MX records are just a bad idea, plain and simple. They don't work the way you'd expect, and virtually no one gets them right. Avoid them
at all costs.
0

Featured Post

On Demand Webinar - Networking for the Cloud Era

This webinar discusses:
-Common barriers companies experience when moving to the cloud
-How SD-WAN changes the way we look at networks
-Best practices customers should employ moving forward with cloud migration
-What happens behind the scenes of SteelConnect’s one-click button

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

rdate is a Linux command and the network time protocol for immediate date and time setup from another machine. The clocks are synchronized by entering rdate with the -s switch (command without switch just checks the time but does not set anything). …
Over the last ten+ years I have seen Linux configuration tools come and go. In the early days there was the tried-and-true, all-powerful linuxconf that many thought would remain the one and only Linux configuration tool until the end of times. Well,…
Learn how to find files with the shell using the find and locate commands. Use locate to find a needle in a haystack.: With locate, check if the file still exists.: Use find to get the actual location of the file.:
How to Install VMware Tools in Red Hat Enterprise Linux 6.4 (RHEL 6.4) Step-by-Step Tutorial
Suggested Courses

636 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question