As far as Exchange 2003 is concerned, migrate the account to AD with Sid
(ADMT), then you can use the Exchange Migration Wizard (if E2k3 is in a
separate org) or the Move Mailbox Wizard (if you joing the x5.5 site) to
move the mailboxes. The exact process depends on whether you want to have
E2k3 join the existing site, or create a new org. If you join the x5.5 site
you want to do ADMT-->ADC-->Move Mailbox.
Inter-org migration from x5.5 to E2k is described in this paper, much is the
same for E2k3:
Microsoft Exchange Support
Please do not send e-mail directly to this alias. This alias is for
newsgroup purposes only.
This posting is provided "AS IS" with no warranties, and confers no rights.