I tried to ssh into my server the other day from behind a very restrictive firewall to read my mail. I found that it wouldn't allow outgoing connections to the standard ssh port (22).
Back at home later I started thinking about installing a web mail program on the server to get around such situations, but eventually solved the problem by doing something much simpler, I configured ssh to listen to more than one port, the second port is a much more commonly allowed port like 80 or 443.
You can do this by configuring multiple Port