Change SMTP Port

[kurgans]

Add line in

/etc/postfix/master.cf

# ==========================================================================

# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
# ==========================================================================
# Entrada normal (puerto 25)

smtp inet n - - - - smtpd
# Entrada en el puerto 999
26 inet n - - - - smtpd ---- new port

/etc/init.d/postfix restart

You server running with port 25 and 26 in smtp

Change port smtp to 26 in configuration client email (outlook, evolution etc...)