Mail ports help

[thedude]

Just signed up for a dedicated server plan because we kept getting our site hacked. I am running Plesk 9.0

Please advise if anyone can instruction or links that would help me

We need if it possible for you to set up your smtp mail server to listen on an additional port that isnt commonly blocked? currently running in to problems not being able to send when traveling with computers ( whether at home or other locations ).
I've seen before where people set up their mail server to listen on port 80 ( which will never be blocked ), in this case i think the same system is doing web and mail, so that wouldnt be an option, but setting it up to listen on port 23 ( telnet ) or port 22 ( ssh ) should be good enough.

THANKS>>>Also if you need anything else from us cause we are new to this please let us know.