Originally Posted by quentusrex
Turns out that comcast is blocking all in and outgoing smtp on port 25. So I had to change the port to 587.
It works now.
did you change default listening port of Postfix?
if so, i think that is not so good way to do it, because now you have to remember this also for internal programs and services.
IMO better is to uncommet submission-line in /etc/postfix/master.cf
submission-module will then relay all incoming smtp to postfix using port 587.
for outgoing i suggest you to use comcast as a relay by modifying /etc/postfix/main.cf something like this:
RELAYHOST = your.comcast-smtp.tld user:pass
this because many mailservers out there blocks mails that are coming fro other than port 25.