1

Background

We use Google Apps for email with our domain example.com:

[ec2-user@example ~]$ dig MX example.com
…
;; ANSWER SECTION:
example.com.            300     IN      MX      1 aspmx.l.google.com.
example.com.            300     IN      MX      5 alt1.aspmx.l.google.com.
example.com.            300     IN      MX      5 alt2.aspmx.l.google.com.
example.com.            300     IN      MX      10 aspmx2.googlemail.com.
example.com.            300     IN      MX      10 aspmx3.googlemail.com.
…

On the same domain we have an EC2 instance running, with Amazon Linux AMI (Centos based). sendmail works fine for non-example.com addresses. However, for example.com-addresses, it tries to deliver mails locally, which fails for users that exist only on Google Apps. Interestingly this is despite local-host-names being empty.

Question

To avoid local delivery attempts, can we set up sendmail so that it sends all email through Google’s SMTP server (requires authentication)? Would that be a good idea? Or is there a better solution?

Additional information

  • Also, it would be interesting to configure the server to send email to local addresses root and ec2-user to the Google Apps user admin@example.com. I guess, we would use mail aliases for that.

  • FQDN:

    [ec2-user@example ~]$ hostname --fqdn
example.com

    Of course, the actual server name is not example.com. It’s another .com domain.

  • As requested by @AndrzejA.Filip:

    [ec2-user@example ~]$ echo '$j' | sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> example.com
> [ec2-user@example ~]$
feklee
  • 505
  • 3
  • 18
  • 1) Is `example.com` set as FQDN of the host? `echo '$j' | sendmail -bt` 2) Does the host accept email from internet? – AnFi Feb 15 '14 at 17:42
  • @AndrzejA.Filip 1) See updated question. 2) All incoming email for the domain is handled by Google Apps, see MX records. – feklee Feb 16 '14 at 11:05

1 Answers1

3

You named your server example.com, the naked domain name. Thus many programs (sendmail included) take you at your word, and consider that the local server does everything related to that domain name.

To resolve the problem, rename the host. For this and a variety of other reasons, no server should ever be named with only its naked domain name.

Michael Hampton
  • 237,123
  • 42
  • 477
  • 940
  • I don't understand this answer, why wouldn't you name the server with only its naked domain name? This didn't solve the same issue I was having. – Mike Kormendy Mar 15 '14 at 22:14
  • @MikeKormendy Then you are clearly _not_ having the same issue. – Michael Hampton Mar 15 '14 at 22:34
  • Regardless of not having the same issue, it would be beneficial if you provided some background on why no server should ever be named with only its naked domain name. – Mike Kormendy Mar 15 '14 at 23:48
  • For posterity, @MichaelHampton addresses the reasons here http://serverfault.com/questions/599712/best-practices-for-fqdn-for-standalone-domain-is-a-two-part-domain-tld-okay/599725#599725 –  Aug 29 '15 at 00:25