>>> 25 is used by your MTA to receive *incoming* messages from other >>> administrative domains (organizations). >> >> Port 25 is never used to submit outbound messages? If not, I'm >> confused as to why Squirrelmail describes its "SMTP Port" setting this >> way: >> >> This is the port to connect to for SMTP. Usually 25. > > It *was* used to submit outbound messages, but this has proven susceptible to > open-relay exploits, etc. > > You're really better off using 587 exclusively.
Is it alright to send on port 25 from Squirrelmail when it's on the same machine as postfix? That way I can make 587 require TLS and authentication but not require that local Squirrelmail encrypt or authenticate. Also, should I have some sort of config that prevents the port 25 open-relay exploit you mentioned? - Grant
