One of our users reported that his Outlook email was not synchronized with the email on his iphone, particularly the SENT items and items that he deleted. One of the things I noticed was that his OST file was named with his email address. None of our other users' OST files are named with their email addresses, but they are named whatever the email profile is named, which is usually their network username. I tried a new Windows profile as well as new Outlook profiles. I don't actually know if this will fix his sync problem, but it's the only thing I see that is different from the other users.