Resolution

For Linux users.

Login to the Plesk server and try "telnet localhost 25", if Plesk SMTP works an output should be:

If you run "telnet localhost 25" on the Plesk server and see another greeting, check article 1374.

Make sure that 'tcp-env' server with appropriate arguments is used in xinetd/inetd configuration for SMTP service.

If you run "telnet localhost 25" on the Plesk server and see something like:

Check if xinetd is running:



If not, try to start it "/etc/init.d/xinetd start". Otherwise, make sure that /etc/xinetd.d/smtp_psa and /etc/xinetd.d/smtps_psa files are OK, compare them with ones from some working server.
Check /var/log/message for possible errors during xinetd service restarting, fix problem and restart xinetd "/etc/init.d/xinetd restart".

If you see in 'messages' an error like:
smtp/tcp server failing (looping), service terminated
see the article 1470.

For FreeBSD users.
On Plesk for FreeBSD, SMTP is run using 'inetd' super-server. So you should check that 'inetd' process is running and /etc/inetd.conf contains records for Plesk SMTP service.