[Postfix-es] Cambiar el puerto 25

[Espartano]

Hola listeros, alquien sabe como cambiar el puerto por default de
postfix, o que escuche en dos puertos simultaneamente ?

de antemano les agradesco cualquier orientacion.
-- 
"Linux is for people who hate Windows, BSD is for people who love UNIX".
"Social Engineer -> Because there is no patch for human stupidity"
"The Unix Guru's View of Sex unzip ; strip ; touch ; grep ; finger ;
mount ; fsck ; more ; yes ; umount ; sleep."
"Documentation is like sex: when it is good, it is very, very good;
and when it is bad, it is better than nothing."