Merging 2 Organizations into one

[AndyNZ]

We are in the process of merging 2 companies and need a way of moving the users Exchange Mailboxes and addresses from one Exchange 2000 server in FOREST\DOMAIN A, to a Exchange 2003 server in FOREST\DOMAIN B.
Is Exmerge the way to go here?
Is there some way of moving mailboxes between Organizations using a trust?

The AD Accounts will be cut over using the AD Migration Tool (ADMT).
Unsure how to move the e-mail though.

All thoughts or suggestions appreciated.

 

[Zelandakh]

Well you have all sorts of options there.

1. The simple way. ADMT then ensure that they all get mailboxes. Then exmerge out and exmerge in. Job done, no worries.

2. The "either it works or it doesn't" way. I've never done this as cross domain! Take the Exchange 2000 store and restore to the Exchange 2003 RSG. Bring that in as an additional store and do a move mailbox. You'll need to sort out AD accounts and mailboxes.

3. The complicated way. Assuming the old Exchange Server isn't on a DC, you can do a server rename using rendom and other command line tools. Then assuming Exchange will start, you can move mailboxes over. Again think about the user accounts.

Personally I'd go for the easy route but remember exmerge loses the single instance storage. So a 10MB in 10 mailboxes will take 10MB on the old server and 100MB on the new server.