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Exchange 2010 to 2013 two separate AD forests

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  • Exchange 2010 to 2013 two separate AD forests


    First, I hope I have framed the question correctly.


    Two Separate Exchange domains with separate Active Directory Forests will be migrated to Exchange 2010. The migration has not been started yet so if it makes sense to migrate them to 2010 and then have one set of users migrate to exchange 2013 then that could be done as well.

    So One domain will be and the other will be - Everything is separate and distinct, no common root domain. Both have been set up as separate AD environments. They are both in the same physical location so logical or network access is available ie. remote connect to either exchange / servers is available to the network admin team.

    Red has approx (150) users and blue has (30)

    The end state desired by the client is one exchange server running 2013 with an Exchange database for the red users and (1) database for the blue users. The Exchange server would be authorized to receive mail for both domains. The active directory permissions would stay separate but exchange would be shared by both organizations.

    Both environments are currently running Server 2003 domain controllers with SP2. Can this be achieved and how?

    The expectation is that the smaller number of users (30) would be joined to the larger organization (red).

    My original thought was to export the (blue) users and import their mailboxes in exchange to a new database. Make Exchange responsible for both mail users. Have the (blue) users connect to Exchange through outlook and login. Neither organization uses public folders so it is just email they are interested in.

    Is that possible?


    Last edited by chbardt; 19th November 2014, 20:09. Reason: Scenario Change

  • #2
    Re: Exchange 2010 to 2013 two separate AD forests

    Linked mailboxes will do the job here.

    However create the mailboxes and include X500 addresses so when you export/import the content to the new platform old email, calendar entries etc still work.

    They will still need an account in the new domain, which after creating the mailbox as linked you can disable. Then just grant the account in the other domain Full Mailbox and Send As. A trust will be required of course.

    Simon Butler
    Exchange MVP

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    • #3
      Re: Exchange 2010 to 2013 two separate AD forests

      Thanks Simon,

      I am assuming that I would bring the other domain up to Exchange 2010 first.
      Create the linked accounts in the blue domain.
      export and import the mailboxes into the domain
      etc. etc.

      When I then deploy Exchange 2013
      Would I be able to then deploy Exchange 2013 and then simply follow the migration process ie. move mailboxes from Exchange 2010 to Exchange 2013 etc.

      Best regards