Posted by Tim Harrington
Fact: Email Address Policies (EAPs) will apply during a mailbox move. While everyone is currently planning on their Exchange migrations to Exchange 2010 :), you will want to take some time to look at your EAPs and users that are exceptions to the policies. The last thing you want is that call right after the migration saying that my email address has changed.
suite: http://howdouc.blogspot.fr/2010/09/email-address-policies-and-mailbox.html