Thank you for replying.
1. did a tail -F /var/log/maillog to watch it
2. set an email to email@example.com
. Using example.com as an example.
3. the logs show that email was received.
4. the logs show that it was sending to the external email.
5. no errors in the log
I also checked /var/log/mailman and could not find any errors.
Checked /var/log/messages too and no errors.
Is there some other logs that I can check?