Diagnosing PMAS failure to authenticate

Learned something about this CentOS 7 Plesk postfix system. If you change smtp in services, postfix will use the new port number for outbound connections too. So to relocate postfix’s inbound connections on 25 need to change them in the master.cf. Or create smtp_alt, not sure one way is better than the other but if it’s in services netstat will name it.

To enable postfix detailed debug, add:

debug_peer_list = 127.0.0.1

to main.cf. Use commas to separate multiple addresses.

Don’t forget the

postfix reload

Also useful is showing what process is using what port (with numeric port #)

lsof -i -P

Running PTSMTP without breaking mail while testing.

So in hindsight this is obvious.  Leave postfix at ports 25 & 587. Set PMAS configuration to use (lets say ports 225 for its inbound connections), and for the outbound side use the standard ports. Remember you *must* run init.d/pmas start after making a change to get the temporary .conf files written out, otherwise ptsmtp will use the config from the last time you ran.

Can even punch a few holes in the firewall to allow outside mail clients to try the PTSMTP listening ports.