Exchange 2003 Cross forest mailbox moves

Now this is a challenge for a weekend migration… Dave is trying to is migrate all of his users from one forest to the other in one hit – qall at the same time, and at the same time migrate the mailbox content, all of the rules and mailbox rights, so all the users will exist with SID history etc. As this is going to happen in one hit – interoperability is not required between the two forests, The accounts just need to be migrated and work exactly the same as they did in the source forest.

Well here’s something you could do…

Migrate NT accounts with ADMT, this will preserve the SID History.
Use the
Exchange Migration Wizard the /m (Clone) option.  The Clone option will preserve the entire mailbox and will preserve rules.  In addition ACL access will contiune to work through the SID history.  Also rules based on e-mail addresses will contiune to work since the Migration wizard will also preserve the old Exchange address in the move. 

The Migration Wizard provides the option to exclude imported messages based on key words in the subject lines of those messages. To use this feature, you must create a subject line exclusion file, saved as a Unicode text file, to use with the Migration Wizard. 
• If you perform more than one migration to the same target mailbox, duplicate messages may be created in that mailbox.
• The Migration Wizard does not change or reconfigure the source mailbox or account. The source mailbox continues to receive mail after you perform a migration. You can configure other recipients to point to the new mailboxes, or remove the original source mailboxes and replicate contacts by using an inter-organizational ADC.
• When you use the Migration Wizard to migrate mailboxes, single instance storage is lost for the migrated data in the target information store. Make sure that enough hard disk space is available to handle the increased storage requirements that this may cause.

Still scary to try in a one hit though – I’d recommend a bit of caution with this in larger organisations…