Migrate from Microsoft Exchange using GAMME
This feature is not available in the legacy free edition of Google Apps.
Migrate your users' mail, contacts, and calendar data from a Microsoft® Exchange server using the Google Apps Migration for Microsoft Exchange tool (or GAMME for short). You can also use GAMME to migrate mail from IMAP servers such as Novell GroupWise®, as well as from other Gmail accounts.
For complete instructions on using GAMME, see the GAMME Administration Guide (PDF).