Adding additional SMTP listener ports
The ZCS MTA can be configured to accept mail traffic on additional SMTP service ports. This means more than one TCP port can be used to bind to the SMTP daemon.
For ZCS servers listening on the default port of 25, /opt/zimbra/postfix/master.cf contains this line:
smtp inet n - n - - smtpd
To add an additional listener port for 2525, insert the the following after the above:
2525 inet n - n - - smtpd
Then, restart the MTA:
# su - zimbra # zmmtactl stop # zmmtactl start
- Do not attempt to bind to ports in use by other applications. This will cause the MTA or other application to fail.
- Backup /opt/zimbra/postfix/master.cf before an upgrade. Changes made to master.cf should only be applied to the current distribution after upgrading.