Help with Mail

I know this is going to sound newbish, and probably is but I am having troubles with the mail.app. Here is my issues, My school doesnt allow smtp or outgoing imap access unless your on campus which I never am. So i signed up for a gmail account and just use their outgoing server. The problem is... All of my replied mail goes to my gmail account and not my school email. How can I fix this?! I think I must be having the same problem with my mac mail as well.

thanks in advanced


Update: gmail lets you set a different reply and send address in settings. Sorry, but anyone that my find this useful... eh.