/var/log/maillog

/var/log/maillog file in Oracle Linux

Ubuntu:

postfix/cleanup
postfix/qmgr
postfix/amavis/smtp
postfix/pipe
postfix/error
postfix/bounce
postfix/smtpd

Sep 25 11:11:11 server postfix/smtpd[1234]: connect from unknown[10.10.10.11] 
Sep 25 11:11:11 server postfix/smtpd[1234]: connect from server.example.com[10.10.10.12] 

/var/log/mail.log in Ubuntu 

See also

• postfix, mailq, main.cf, mail.log, pickup, /etc/postfix/main.cf, Postfix releases, /var/log/mail.log, /var/log/maillog, smtpd