Exchange 5.5 to 2003 migration

Hi all,

I'm working on a domain migration from Windows NT to Windows 2003.  Everything is fine.  I'm using SID history so users can access resources in either domain.

Now they want me to migrate to Exchange 2003.  We currently have two Exchange 5.5 servers in the NT domain servicing lots of email domains for Citrix customers.  The mailboxes on the Exchange 5.5 servers are configured to use the Windows 2003 domain user accounts as the "primary user account".

After the migration, we'll end up with 2 Exchange 5.5 servers hosting the customer email domains and one Exchange 2003 server hosting our company email domains.  We don't have many users here (we do 1000 Citrix customers though) so I thought I'd just exmerge the mailboxes from the 5.5 server to the 2003 server.

I don't really know the best way to handle the migration so I have a few questions:

1.  Can you have Exchange 5.5 servers (along with the Exchange 2003 server) in a Windows 2003 domain?

2.  Would I have to install the Exchange 2003 server in the same organisation at the 5.5 servers to be able to use their global address list?

3.  After mailbox enabling the Windows 2003 users, would it be possible to have one outlook profile connecting to the 2003 mailbox, and one outlook profile pointing to an Exchange 5.5 mailbox?
This problably won't be necessary, but I'd like to know if it's possible.

4.  Exmerge question.  You know old pst files have a 2GB limit, but pst files created with Outlook 2003 (or later) have a 20GB limit, are there limits on the pst files created by Exmerge?  Can I use Exchange 2003's Exmerge on the Exchange 5.5 mailboxes?  The reason I ask is that there are a few mailboxes on the 5.5 server that are over 2GB.

Thanks for any input.
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kanalQkoTechnical Support EngineerCommented:
1 > yes you can, but not recommended
2 > yes you have to add in the same organisation level
3 > yes it`s possible
4 > not recommended to have large-sized pst more than 2 gb

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DarylxAuthor Commented:
I know a large pst file isnt' recommended but some of the mailboxes are more than 2GB.

With the Outlook 2003 pst file format, the pst file can be up to 20 GB.  

Does Exchange 2003's version of Exmerge create pst files in the later format?
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