Connect to a Plesk server via SSH.
Create a copy “postfix” configuration file:
# cp -a /etc/postfix/main.cf /root/backup_main.cf
Open “postfix” configuration file in a text editor, for example, “vi” editor:
# vi /etc/postfix/main.cf
Add the lines specified below to the configuration file main.cf and make sure that these lines are present only once in the file:
Note: replace example.com with required mail server name.
myhostname = example.com smtpd_banner = $myhostname ESMTP $mail_name
Using command line tool. check “postfix” configuration syntax and restart postfix:
postfix check (empty output - means syntax is OK)
# service postfix restart