Outlook 2003 Fax Problem

Just need some quick help here.. the Sales dept. at my job send a lot of faxes, and they would always recieve an email that notifies them if it's sent. Recently, however, the notification stopped being sent and some of them have been asking to fix it. It's not quite my job since I'm only a help desk type, but since I want to move into network administration I'm trying to learn what to do.

Anyways, is this a configuration issue with Outlook or Exchange, and how would I go about fixing it? I've never worked with Exchange Server before, so any help with this will be greatly appreciated.

Thanks!