You can
change the SMTP port if you have access to the Exchange Server[
^]. And then use it with the port you specified.
I seriously doubt that the school would open strange ports for your usage... but you can give it a shot.
You could also try to bypass by using standard ports that are usually used for other communications, like port 80 which is used for HTTP, port 21 which is used for FTP etc...
Good luck,
Edo