In order to see the mail log files, you should be logged into SSH as root. The qmail logs are located in the following directory:
/usr/local/psa/var/log/maillog
You can use the following command to view your qmail logs:
tail -f /usr/local/psa/var/log/maillog
Here’s a typical log sequence showing the complete transmission of one piece of mail:
Oct 3 16:50:19 dv35 qmail: 1223077819.930048 new msg 163786382
Oct 3 16:50:19 dv35 qmail: 1223077819.930096 info msg 163786382: bytes 860 from <> qp 24106 uid 2522
Oct 3 16:50:19 dv35 qmail: 1223077819.937789 starting delivery 2: msg 163786382 to local 2-user@example.com
Oct 3 16:50:19 dv35 qmail: 1223077819.937835 status: local 1/10 remote 0/20
Oct 3 16:50:19 dv35 qmail-local-handlers[24107]: Handlers Filter before-local for qmail started ...
Oct 3 16:50:19 dv35 qmail-local-handlers[24107]: from=
Oct 3 16:50:19 dv35 qmail-local-handlers[24107]: to=user@example.com
Oct 3 16:50:20 dv35 qmail: 1223077820.159866 delivery 2: success: did_0+0+2/
Oct 3 16:50:20 dv35 qmail: 1223077820.160087 status: local 0/10 remote 0/20
Oct 3 16:50:20 dv35 qmail: 1223077820.160159 end msg 163786382