Exchange 2003 coexistance between multiple domains

Posted on 2006-06-01
Last Modified: 2010-03-06
My company has two locations with two seperate Active Directory Forests.  We had an exchange org that contained two administrative groups with mail that flowed from our exchange server (point of entry) in location A over MTA to exchange server at location b in the other administrative group.  We added Exchange 2003 servers and left our 5.5 servers in place acting as a bridgehead to the one 5.5 server at our remote location.  Also: everyone at both sites have the same email address.  I had my connectors in place and felt that due to power issues in my server room that I would remove the old 5.5 servers after pointing the remote bridgehead server to my local bhs.  After I removed the 5.5 servers at location A, I could no longer see site B in ESM. I have recently done a lot of post homework that should have been done first, because now I found out that Exchange 2003 has to be a seperate org for each forest.  The reason this is so critical is now when I create a new user at location A in AD and create a mailbox, it will not get replicated to the site b.  Nobody in site b can send email to new users in site A that were created after removing the 5.5 servers.  Since I know that if company A purchases company B you can integrate exchange servers using a routing group connector, is there any hope of getting a 2003 server in site b (different domain) to talk to my exchange server at location A and receive mail at the same .com email address as lcation A?
Question by:csjackson
    LVL 11

    Accepted Solution

    It is true that each Exchange organization is specific to one Active Directory forest. However, multiple forests can use the same Exchange organization for mail service.
    Here is a very good White Paper which explains in details how to achieve this:

    The best approach would be to perform consolidation. Using ADMT v3 will help you move the computer and user accounts (including user and outlook profiles). Exchange migartion wizard can help you move the mailboxes.
    Based on your company policies you can decide to have two separate domains or one domain and two separate sites.


    Author Comment

    My big problem is accountability.  Loc. B needs to have their own server and remain their own domain for now.  There are more politics involved then issues with Exchange.

    Author Comment

    Hi Dean,

    Thanks for your help.  I went to the site to download the multiforest doc and it seems to be corrupted.  Is there anywhere else I may be able to find it?  Thanks
    LVL 11

    Expert Comment

    by:NetoMeter Screencasts
    You should be able to open the doc file now.
    Location B can have their own server and domain in the same forest which will save a lot of troubles in the future.

    LVL 9

    Expert Comment


    Your cause is JUST!!! :)

    Your current situation is not too good since the replication between exchange server's in the 2 sites is not happening anymore.

    You may want to have the exchange server 5.5 in the other site untill you plan to remove it and replce it with exchange 2003 or have it as it is and get some workaround from me to route internet emails to them, and also establish internal mailflow.

    If you wish to have 2 AD ORG and 2 different Exchange Orgs with the same SMTP domain name, Know what??? IT'S POSSIBLE.

    Please let me know and we can plan it the right way!! :)


    Author Comment

    The multiforest word doc was extremely helpful. After presenting my plan which also included stuffing another server which will host the MMS services into my already overcrowded server room, it became more feasible to finnaly concede to the idea that developing a new domain within our forest was the best idea.  Thanks

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