Symptoms
-
Mail to an external domain is not delivered. The following entries can be found in
/var/log/maillog
:# status=bounced (mail for example.com loops back to myself)
# postfix/smtp[30738]: warning: host mail.example.com[203.0.113.2]:25 greeted me with my own hostname c1.example.com
-
Unable to get root email delivered externally. In
/etc/aliases
the following entries can be found:# tail /etc/aliases
# Person who should get root's mail
root: johndoe@example.com
Cause
The remote server thinks that he is sending mail to itself. Possible reasons:
- IP Address of MX record for recipient's domain points to Plesk server
-
myhostname
parameter in/etc/postfix/main.cf
is the same on both sender and recipient servers
Resolution
-
Connect to the server via SSH.
-
Make sure first that IP address of the recipient's domain does not belong to the Plesk server:
# host example.com
example.com has address 203.0.113.2
example.com mail is handled by 0 example.com.
# ip a | grep 203.0.113.2
inet 203.0.113.2/32 brd 203.0.113.2 scope global venet0:0On the example above, IP address 203.0.113.2 belongs to sender server. That is why Postfix falls in a loop.
Correct the DNS setting to resolve the issue. If DNS is handled by a third-party name server, correct DNS settings in Plesk accordingly.
-
In case IP address does not point to the same server, check
myhostname
on a source and compare with hostname from the log:# postconf | grep myhostname
myhostname = c1.example.com
# postfix/smtp[30738]: warning: host mail.example.com[129.168.0.1]:25 greeted me with my own hostname c1.example.comIf they are equal, it is required to change
myhostname
in/etc/postfix/main.cf
file. -
As an additional step, it may be necessary to add a required domain name to
mydestination
line. It should look as follows:mydestination = localdomain, localhost, localhost.localdomain, localhost, example.com
and restart postfix using the following command:
# service postfix restart