Printer Brother MFC 7420

Hi, I just switched from a PC to an iMac. Everything runs just perfectly, except the printer which worked just fine under XP. It is connected to an Airport Extreme (to which my old PC is also connected via Bonjour). Printing works from a document I open in Word or Excel, but if I try to print an email nothing happens. I get a message saying No pages found. Offline. Has anyone experienced this or have any information as to what I can do. Thanks.