I was trying to route emails from one MTA to postfix, so I needed to change the port that postfix was using, so this is what I did:
First, please backup the file in case you break something
cp /etc/postfix/master.cf /etc/postfix/master.cf.bak
Let’s edit the following file:
vim /etc/postfix/master.cf
Make it look like this:
==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
# ==========================================================================
#smtp inet n - n - - smtpd
2525 inet n - n - - smtpd ## This is the new port
Restart postfix and verify by running the following commands:
systemctl restart postfix
netstat -plutn | grep 2525
There you go!
P.S. Millennials are allowed to use nano