I recently had the task to create a few hundred email contacts for exchange 2010 server. I then ran into a problem that made me scratch my head for little while. I had a user that was sending emails and the recipients were receiving winmail.dat files instead of the attachments that was actually sent with email. After some deductive reasoning I cam to realize that it was the contact that I made. The were all set to USE MAPI rich text format.. which was causing the issue. I went back to my command to create the contacts and added the parameter -UsePreferMessageFormat ($false) which should translate to "Never" but it doesn't seem to work. I tried several ways to do it and every time it comes up <not set> which translates to Use default Settings........Does anyone have a way to get this actually work. Am I missing something?