Exchange 2003 & Exchange 2013

I need move my users to a new domain (parent company says so) but I also need to retire Exchange 2003. I will like to do the transition over a period of time therefore I will have a trust in place.

Currently users are on Exchange 2003 but my new domain will have Exchange 2014, is it possible to setup a connector from Exchange 2003 Domain A to Exchange 2014 Domain B that will allow me to have both domain running at the same time, and the user will not notice?

I am happy to export/import the mailboxes if need be, it is more the flow of mail, users in both domains need to be able to use Outlook to send and receive.
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Simon Butler (Sembee)ConsultantCommented:
Are the two Exchange platforms in the same FOREST? If not then you are looking at cross forest migration. 2003 to 2013 cross forest isn't possible, so it will have to be an export/import. Doing this transparently is impossible. The users will notice and it will have an impact.

How many users are we talking about?

Carpe--DiemAuthor Commented:
Yes the domains are in the same forest, about 250 users, yes I understand that users will be impacted but what I meant was that if I transferred a couple of users account on Friday to the new domain, on monday they could log in and send/receive emails while the users are still working in the old domain, i.e both domains working side by side.
Will SzymkowskiSenior Solution ArchitectCommented:
As stated you cannot do this directly from 2003 - 2013 (no upgrade path available). You would need to use Exmerge to export the mailboxes via PST and then import them into the new environment after the AD accounts have been migrated over, or simple re-created in Forest B.

Steps to follow...
- Create a Forest Trust bi-directional Forest A/ForestB
- use the ADMT to migrate AD Users to Forest B
- Use Exmerge to Export the Exchange Mailboxes from Forest A
- Import the PST files into Forest B (powershell)
- Have the Forest A users use OWA or configure Outlook to connect to Forest B Exchange

Note: This option would be time consuming if you have several mailboxes in Forest A.

If you have a lot of mailboxes then you might want to Upgrade to Exchange 2007 or 2010 and create linked mailboxes in Forest B to Forest A.

ADMT Manual:


Linked Mailboxes:


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Will SzymkowskiSenior Solution ArchitectCommented:
You could do them in batches and they could connect to their new mailbox in Domain B using OWA.
Simon Butler (Sembee)ConsultantCommented:
If they are in the same forest, then I would be very surprised if Exchange 2013 is installed, because the presense of 2003 should block it. There is no upgrade path.

If everything is in the same forest then you should be able to move the mailboxes because Exchange operates at the forest level.

However I would first check with corporate to see whether it is Exchange 2013 they have installed - if it is, they are probably in an unsupported scenario because of the presense of your Exchange 2003 server.

Carpe--DiemAuthor Commented:
It will be a brand new exchange 2013, I am installing it in a brand new domain next week.. I was wondering if there is a way both by exchange 2003 and 2013 can co exist, it is not an upgrade.

Can mail arrive in my 2003 exchange and be passed to the exchange 2013? that's probably a simpler way of asking my question.

All the other parts, exports/imports, forests, updating users settings I can work out later, i just need to know if it feasible.
Will SzymkowskiSenior Solution ArchitectCommented:
If you have Exchange 2003 in the forest you cannot successfully install Exchange 2013 in the environment. You need to upgrade to at least 2007 for this to work. When you install Exchange 2013  in the forest it modifies the Schema (forest role) which allows 2007 and 2010 exchange to communicate. If you have 2003 in the forest the schema update will/should fail.

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Carpe--DiemAuthor Commented:
okay it looks like a 2phase update then.
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