We've deployed Outlook 2010/Windows 7/Internet Explorer 9 to our Windows domain but are now having the issue that html forms with build in mailto/post functionality are not working as expected. The email is generated without the body and is not automatically sent. User's don't get the "A program is trying to automatically send email on your behalf" notification at all. I've tested the same forms on a stand alone box with the same set-up and this works fine so it must be something on our GPOs/Exchange 2007/possibly a Microsoft Update that is restricting this but I really can't work out what.
You can reproduce this issue with the Form example here:
http://support.microsoft.com/kb/279460