I didn't know enough about what was going on when I posted this question. For security reasons, SMTP is disabled on Microsoft Exchange, so Exchange is using some Microsoft Protocol to send the email. I added the MAPI control to my application and used Microsoft Outlook Internet Settings as my username. This seems to work fine on my machine. I think everyone is using Microsoft Outlook, but I guess if they aren't then I will have a problem. Is there a better way to send the email than using the MAPI control?