Thanks for all the help, I guessed that it was like that, but I just wanted to make sure we could "save the messages" for the remote offices. I was worried I'd have to go OWA, but if the messages are saved, IMAP will be better.
p.s. hardwareguy: Thanks for the bonus hint! I'll have to make sure to setup instruction sheets on how to configure IMAP accounts for the users if they use this at home. I'd hate to have to explain that to these guys, they're not what you'd call "computer savvy"