Linux Mail Server Setup and Howto Guide

Hi Raminda,

What messages is the primary server rejecting? Messages from the backup mx or messages sent to the primary server for delivery?

Hi Raminda,

It looks like your configuration rejects unknown hostname, something like reject_unknown_helo_hostname. You need to configure your primary mail server to accept mail from your backup server.

Hi Raminda,

You can remove reject_unknown_helo_hostname since most Exchange server will fail that test.

But if you prefer to retain it, add permit_mynetworks before the reject_unknown_helo_hostname and in mynetworks, add the IP address of your backup server. If you are still having problems doing this, post you configuration using

postconf -n

since I'm just guessing you configuration.