Outlook 2007 not displaying winmail.dat contents in mail.

Hi,

We have a some users who are receiving winmail.dat rather than mime encoded html email. From my understanding of the format, these users email client (Outlook 2007) should still be able to integrate and display the information. But this is not so. We're not using Exchange.

How do I resolve this issue? Is it possible to do from my end? Why do some users receive the mime encoded html whilst others receive winmail.dat from the same email? (ie: same email sent to 2 people in the company, one gets one format whilst the other gets another).

I know this is a tricky one, I've spent countless hours working on it with my team. Just hoping someone here knows the solution.