Private IP / 25: socket error

I’ve got a server with a shared IP and 4 virtual servers using private IP’s. Two of the private IP’s are receiving mail fine, but the other two are not and after a few days kick back the error message:

Message will be retried for 1 more day(s)

Technical details of temporary failure:
The recipient server did not accept our requests to connect.

I can not figure out the difference between the ones working vs not working. Any advise would be appreciated.


Virtualmin Pro
CentOS 7


Hmm, is Postfix listening for connections on that IP?

You can determine that by running this command:

netstat -an | grep :25

Thanks Eric,

No, just the shared and two of four privates.

tcp 0 0* LISTEN
tcp 0 0* LISTEN
tcp 0 0* LISTEN
tcp 0 0* LISTEN

Okay, that may be the key then.

We need to get it listening on all the IP’s.

That’s configurable in /etc/postfix/

You’d want to make sure that you have a line that looks something like this, for each of your IP addresses: inet n - - - - smtpd -o smtpd_sasl_auth_enable=yes

Thanks so much Eric, That did it!

I notice the other two that were working were in there of course, but they had their SSL cert info appended to the line. So must be I did something slightly different when I added the cert to those.

To make things more of a mystery, the broken ones show receiving email up to a few days ago and then stopped. Don’t know how the dropped them.