If you are on a hosted mail system like Microsoft Exchange Server you may find that the costs are running away with you.
Fortunately there is a cheap, and just as effective, alternative: Google Apps Premier.
For just $50 a year (at the time of writing) you can have all of the functionality of Exchange Server.
Transition is made very easy by the Google Apps Sync application, and from within your WebMe Domain Control Panel you can make all of the necessary DNS changes with just a click of a button.