Email to my organization (mycompany.com) goes through 2 sendmail servers running on CentOs 5.6, mail01 and mail02. I've configured a new sendmail server, mail03, in a different site for DR purposes, and am now testing it.

I haven't got the public MX records set up to point to the new server yet since that requires some red tape to get through, so I decided to test the new server internally. I started a telnet session from mail02 to mail03 port 25, and typed in the SMTP commands to send an email from gmail to me@mycompany.com. I receive the email, but I noticed that mail03 is relaying the mail to mail01 first, then mail01 delivers it to my internal exchange server. I have the mailertable feature enabled and a entry for mycompany.com that points directly to my exchange server, so I don't know why it would relay the mail somewhere else.

I couldn't find any configuration that would do that, so i thought it must be a DNS issue. Since I do not have the authority to change the public DNS records, I set up a test DNS server that contains an MX record for mycompany.com that points to mail03.

This time, sending a mail gets this error:

Dec 30 03:53:21 mail03 sendmail[1886]: rBU3qVcM001880: SYSERR(root): mail3.mycompany.com. config error: mail loops back to me (MX problem?)

Perhaps there is a setting that tells sendmail that its responsible for a domain or something? I don't remember having this problem when I set up the other 2 servers. Any help would be appreciated.

  • The server is not using the mailertable. Either the mailertable is wrong, or the configuration telling sendmail to use the mailertable is wrong. I can't say more than that without seeing the configuration. – Jenny D Dec 30 '13 at 10:52
  • 1
    You say "I have the mailertable feature enabled and a entry for mycompany.com that points directly to my exchange server"; please show us this, instead of just telling us. – MadHatter Dec 30 '13 at 10:53
  • Can you provide the contents of /etc/mail/access and /etc/mail/sendmail.mc? You might need to scrub them for private information but it would help to provide more context on the setup here. – Mike B Dec 30 '13 at 16:20

As it turns out, it had nothing to do with sendmail's configuration. When I edited the resolv.conf file for the new server, I added in the nameserver entry, but did not edit the search domain entry, which was left as 'domain.org'. After changing that to 'mycompany.com', mail started relaying properly.

I don't know why this would make a difference though.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.