Exchange 2003 / 2007 Routing Question

Posted on 2010-09-10
Last Modified: 2012-05-10
We have two organisations that currently reside within a single Windows 2003 AD Forest in two seperate domains. Within Domain A there is a Exchange 2007 server and within Domain B there is an Exchange 2003 server. These servers reside within the same Exchange organisation in two sites and are linked via a routing group connector. Each server has seperate site specific SMTP connectors to Mimecast and handle there own email. All PC's are using Outlook 2003 for connectivity. As there is a single server for each company these servers are gateways and mailbox / PF servers.

The companies are splitting so we have had to build a new Windows 2008 AD forest. Within this forest is a new Windows 2008 and Exchange organisation on an Exchange 2007 server. We have to move all of the users and mailboxes from Domain B into the new forest. Once the migration of all systems are complete the links between the companies will be broken and the existing forest cleaned up. However this clean up wont happen until several weeks after the Exchange migration has happened

I have tested the use of the Ex2007 move-mailbox cmdlet and will be using this to migrate the mailboxes to the new server / Org. I was planning on doing an Outlook Public folder export / import via a PST file to handle the public folder user data. However I have concerns about some of the system PF's specifically the Free / Busy information. I cannot see how to migrate this information and I'm not sure what the impact will be for the users. Can you explain?

I also have a question with regards to message routing. Once the mailboxes are moved into the new Forest staff in Domain A will still need to email people in the new forest. However as the old server from Domain B will still remain in the short term how do i stop Domain A's server trying to send messages to Domain B instead of the new server in the new Forest? What is the easiest / best method of overcoming this issue. Do I just have to have to uninstall Exchange from Dmain B or is it as simple as removing the routing group connector, changing the authorative domains for the organisation or something else.....

Many Thanks

Question by:Ozannes
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Expert Comment

ID: 33644744
Are you looking at sharing free busy info between the orgs until you split them?
If so you could start be looking at the Interorg replciation tool

Worth reading this as its is really a 2003 tool...

Of course Quest etc make tools for this sort of thing as well ;-)

In Exchange 2007 the availablity service provides the free busy functionality for Outlook 2007 / 2010 and OWA clients
Public folders are only needed for pre-2007 Outlook clients and obviously if you are using then to store existing data.

LVL 31

Expert Comment

ID: 33644946
I wouldn't worry too much about migrating the Free/Busy as the Availability service will read it from the mailboxes on Exchange 2007 and above. Like what ARE71 said...

As for the message routing, you either need to get rid of those mailboxes and convert them into Contacts so the messages go out via the internet or create contacts with bogus address like and then create a connector to send everything with that address space direct to the e2k7 server, then you will also have to add these e-mail addresses to everyone in the new Org. That's why it is probably easier to just get rid of domainB so all messages to this domain go out to the internet and are routed from there.

Author Comment

ID: 33645026
Many thanks for the info I'll take a look at the inter org replication tool.

In terms of the availability service I thought that this was only for Outlook 2007 and as we are using 2003 it wouldnt be used.

Domain B has a number of other servers (non Exchange) in it which cant be got removed immediately as they are being accessed via SID history from users in the new forest. So the domain iteself cannot be removed.

However based on your reply I assume that the only way of ensuring Domain A can still email the new forest is to uninstall Domain  B Ex2003 server and remove that site. This would mean all users in Domain A would send message via our normal internet bound SMTP connectors to Mimecast?
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LVL 31

Accepted Solution

MegaNuk3 earned 250 total points
ID: 33645098
Your 2 options are:
1.) Remove DomainB Ex2003 server and AG/RG
2.) Go for coexistence approach that I mentioned earlier where the old mailboxes forward to the new ones.

Yep, Outlook 2003 needs PFs for Free/Busy, but I still wouldn't worry about migrating it because as the Outlook 2003 clients come online on the new Exchange 2007 server they will republish their Free/Busy info into the new public folders (normally within 15 minutes).

More reading on the Availability Service and older clients:

Assisted Solution

ARE71 earned 250 total points
ID: 33645131
Availability Service is for 2007/2010 clients. If older you need public folders and the free/busy data will be created in the system folder from the mailboxes. Don;t worry about moving it, it will go with the mailboxes.
Interorg replication is for sharing it between both orgs.
Have to agree with MegaNuk3 for routing of emails. You can look at creating connectors and making domain names authoriative and non-authoriative (i.e. if authorative it will NDR if a mail address does not exist, non-authoritive will look to forward on to another, normally authorative, server based on your routing configuration), but you will need to think through and plan your mail flows.

Best advise is to keep it simple.

Author Closing Comment

ID: 33645145
Many Thanks for the advice I like the idea of simple so will be uninstalling the old server, site etc.
LVL 31

Expert Comment

ID: 33645161
Thanks for the points.
Be careful about Outlook cached entries for your users in Domain A cause if they try and send to an old cached entry for someone in Domain B they will get a nice NDR, so it might be worth having some Contacts or stub mailboxes in your AD with X500 addresses to stop your users in Domain A getting NDRs or you can tell them not to us cached entries for for Domain B users, but we all know users never listen... ;-)

Expert Comment

ID: 33645233
If you can get away with it use Group policy to turn off the Outlook Autocomplete during the migration.
LVL 31

Expert Comment

ID: 33645270
Losing autocomplete will make lots of users very angry, at least that's what normally happens in the places I have worked... ;-) Cause the users normally don't have everyone they send external mails to in their Contacts...

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