Active Directory Migration 2003 to 2008 R2

A few years ago in a past life I performed an Active Directory inter-forest migration from domain functional level 2003 to 2008R2 using ADMT 3.2 and PES 3.1 (x64/x86). An Exchange Server mailbox migration from 2007 to 2010 was performed simultaneously. The one problem I ran into was that the old X.500 addresses for the mailboxes aren’t migrated to the new mail system. The cached auto-complete email addresses in Outlook use the X.500 address for internal emails which caused internal to internal email to fail. Once the auto-complete addresses were wiped out everything was fine and Outlook began creating new