I am currently using InfoPath, SharePoint, Exchange 2007 and ActiveSync. When I send an InfoPath form to a user everything works fine in their Outlook, but when they go to sync their mobile devices they get an error message about not being able to sync. I am not sure if signing or certifying the form is the answer but I have tried playing with both and I still cannot get it to sync. Once you delete or move the email with the InfoPath form in it the mail syncs right up. Thanks in Advance, Mike