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merging 2 organizations and running mail for 2 organizations/domains on one exchange server

dustaine asked
Last Modified: 2013-12-19
I have 2 separate organizations, domains, and forests.  They are are linked together by a domain trust.  As of yet I do not have a federated trust between exchange servers. Eventually these 2 organizations will merge into one organization. Basically one will for the most part absorbed the other. Many users of the one organization will be absorbed into the other organization while others will stay with the old organization.  This will include mailboxes.  I want to know if there is a way I can use the Exchange server of the old organization to host old email as well as set up a database etc for the new organization.  basically I would like it to do mail@originalco.com and mail@newco.com. Basically I want to continue to use as much of the old infrastructure as possible but transition it to the new company/new domain. I would like to set them up independently, but part of the same domain.  Similar to having an office in NC and an office in MI all part of teh same domain but connected by MPLS.  The great thing about the old organization is that it is across the hall and connected by Ethernet cable.  I know this is somewhat vague as I am not sure how to put into words what I am envisioning.
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Most Valuable Expert 2014

Technically it is possible. You would need to use Outlook 2010 so you can connect two different Exchange orgs. However the major problem is going to be mail routing, things could get very confusing very quickly.
What you could do is move the users on to the preferred platform, remove Exchange from the old domain, rebuild the server with a fresh installation of Exchange and then move content around.


What you're referring to Simon (correct me if I'm wrong) is essentially what I said, where you'd migrate the old exchange infrastructure and address space into the new domain, correct?


My thought is that I would need to create a new domain... Company B.local to match what they will be merging into, set up a domain controller and exchange server. then set up routing between the two locations much like I have now, but with a different address space.... 10.0.x.x is my NC location and 10.1.x.x is the home Michigan location. The old company is 10.2.x.x.  I figure I could make the new segment 10.3.x.x Set up the Exchange server to mimic the new organization and set up its users in AD/Exchange.  That way I could make sure the new segment is visible and routing for whenever the go live date will be. I have never merged an organization so this is all new to me. I have set up independent organizations, but that is it.  Thankfully both organizations have very similar setups... All Exchange 2010, server 2008 functional level, all on VM Ware.

I think you're going through a ton of work for very little gain, but I'm also not too clear on what you're last post was explaining.
Most Valuable Expert 2014

You can't migrate the old Exchange infrastructure in to the new domain, because you cannot take Exchange from one forest and put it in to another. The most you can do is use the hardware and licence for a new build.

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