Why is Postfix able to send emails to other domains but not its own domain?

Question

I set up an SMTP server on a CentOS 7 droplet. Emails are successfully being sent to Gmail accounts, but they are failing to send to my G Suite email accounts.

Successful email:

Jan 1 13:35:48 Production postfix/smtp[2869]: E5B653FDBA: to=personal_email_address@gmail.com, relay=gmail-smtp-in.l.google.com[209.85.144.27]:25, delay=877, delays=876/0.02/0.31/0.25, dsn=2.0.0, status=sent (250 2.0.0 OK 1483295748 k58si25466087qta.76 - gsmtp)

Failed email:

Jan 1 13:35:48 Production postfix/lmtp[2871]: E5B653FDBA: to=root@example.com, orig_to=support@example.com, relay=none, delay=876, delays=876/0.02/0.02/0, dsn=4.4.1, status=deferred (connect to example.com[/var/lib/imap/socket/lmtp]: No such file or directory) Jan 1 13:35:48 Production postfix/smtp[2869]: connect to gmail-smtp-in.l.google.com[2607:f8b0:400d:c0e::1b]:25: Network is unreachable

I replaced my domain name with example.com above.

I was able to fix the “Network is unreachable” by opening /etc/postfix/main.cf and setting the following:

inet_protocols = ipv4

However, the other error is still present, and emails are still failing to send to my domain accounts:

Jan 1 17:22:38 Production postfix/lmtp[4066]: 9EC3E3FE3C: to=root@example.com, orig_to=support@example.com, relay=none, delay=1104, delays=1104/0.03/0.01/0, dsn=4.4.1, status=deferred (connect to example.com[/var/lib/imap/socket/lmtp]: No such file or directory)

Why is Postfix able to send emails to all domains except the one that it’s running from? How can this be fixed?

andrewl85 · Answer

I think I figured it out. I opened /etc/postfix/main.cf file and changed this line:

mydestination = $myhostname, localhost

to:

mydestination = localhost

Then I ran ‘service postfix restart’ to restart Postfix. It’s sending emails to my domain now. Thanks for your help!

popovtv · Answer

Hi,

I still have the same problem as in topic. But my GMAIL answer is:

Apr 15 10:59:31 server postfix/pickup[14501]: 841DDC0A50: uid=0 from=<root>
Apr 15 10:59:31 server postfix/cleanup[14853]: 841DDC0A50: message-id=<20170415075931.841DDC0A50@MYDOMAIN.COM>
Apr 15 10:59:31 server opendkim[20771]: 841DDC0A50: DKIM-Signature field added (s=SERVER, d=MYDOMAIN.COM)
Apr 15 10:59:31 server postfix/qmgr[14502]: 841DDC0A50: from=<root@MYDOMAIN.COM>, size=457, nrcpt=1 (queue active)
Apr 15 10:59:31 server postfix/smtp[14846]: 841DDC0A50: host ASPMX.L.GOOGLE.COM[173.194.79.27] said: 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered. Please resend your 450-4.2.1 message at a later time. If the user is able to receive mail at that 450-4.2.1 time, your message will be delivered. For more information, please 450-4.2.1 visit 450 4.2.1  https://support.google.com/mail/?p=ReceivingRate j125si2027576wmj.50 - gsmtp (in reply to RCPT TO command)
Apr 15 10:59:33 server postfix/smtp[14846]: 841DDC0A50: to=<ME@MYDOMAIN.COM>, relay=ALT2.ASPMX.L.GOOGLE.COM[64.233.188.26]:25, delay=1.7, delays=0.05/0/1.3/0.39, dsn=4.2.1, status=deferred (host ALT2.ASPMX.L.GOOGLE.COM[64.233.188.26] said: 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered. Please resend your 450-4.2.1 message at a later time. If the user is able to receive mail at that 450-4.2.1 time, your message will be delivered. For more information, please 450-4.2.1 visit 450 4.2.1  https://support.google.com/mail/?p=ReceivingRate u13si4905019pfg.6 - gsmtp (in reply to RCPT TO command))

Changing mydestination to localhost doesn’t help.

All other emails are delivered.

Maybe I need some additional settings of relay or transport maps? Because from any other servers messages are delivered to @MYDOMAIN as usual. Thanks.

andrewl85 · Answer

Thanks for responding, but what exactly do I turn off? Are you referring to a certain setting in the main.cf file?

Woet · Answer

Since the hostname of the server matches the domain, it tries to deliver locally instead. Turn it off.

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Why is Postfix able to send emails to other domains but not its own domain?

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