Is there an advantage, Postfix vs. Exim? Is one more secure then the other? What about configuration? and Documentation?
No, not in general. Some things are easier to configure in postfix, others are easier in exim. This depends all on your mail setup. I heard that postfix shall be a bit faster then exim, but this will become relevant mostly if you try to handle several hundred thousand mails a day. But I never benchmarked both solutions and the speed will vary on your type of configuration too. Postfix and exim are both very secure. There is many good documentation out there for both mailservsers. Maybe it is better when you describe what kind of mailserver setup you need so we might suggest you a good howto for it.
What I'm trying to do..... My mail set up is simple, but has been a pain to set up. I receive and process inbound mail, provide web mail, POP3 and IMAP access. For outbound ( and this is where the problem starts) I relay my mail through a DYNDNS server (outbound.mailhop.org). The problem that I run into is with the relayhost and using a port other then 25.
Did you take a look here? http://www.howtoforge.com/postfix_relaying_through_another_mailserver If you use a port different from 25 (e.g. 2525) on the relay server, I'd use Code: echo "smtp.example.com:2525 someuser:howtoforge" > /etc/postfix/sasl_passwd
