Mail to anexternal domain is not delivered. The following information can be found in
status=bounced (mail for example.com loops back to myself)
IP Address of MX record for recepient's domain points to Plesk server. So, Postfix tries to send email to itself.
Check if IP address of the recepient's domain belongs to the Plesk server:
example.com has address 203.0.113.2
example.com mail is handled by 0 example.com.
# ifconfig | grep 203.0.113.2
inet addr:203.0.113.2 Bcast:203.0.113.15 Mask:255.255.255.0
# cat /etc/sysconfig/network-scripts/ifcfg-eth0-range0
On the example above IP address 203.0.113.2 belongs to sender server. That is why Postfix falls in loop.
In this case, delete IP address 203.0.113.2 from Plesk server and restart network service:
# service network restart
After that, make sure that IP address 203.0.113.2 does not point to the server anymore.
Note: If the maillog contains the server name, instead of domain name, please, add the server name '
server1.net ' to the
mydestination line in
/etc/postfix/main.cf and then, restart Postfix:
# grep mydestination /etc/postfix/main.cf
mydestination = localhost.$mydomain, localhost, localhost.localdomain, server1.net