We have an Exchange 5.5 server in a child domain pulling its users from the parent domain. Looking to build a new Exchange 2007 server in its own child domain to migrate users out and looking at building the new child domain and install the new Exchange, then Exmerge mailboxes over to the new box. Questions are:Is it possible to install the Exchange 2k7 ahead of time in the child domain without breaking the Existing Exchange 5.5? or is the 2K7 going to want to repopulate the parent AD with its info and break 5.5 or cause conflicts?If we do this will the users Outlook profiles find their new mailboxes and server name on their own?

Direct migration from 5.5 to E2K7 not supported. http://msexchangeteam.com/archive/2006/11/29/431687.aspxYou might need to do the migration in two steps.Raj

I am aware of that, not looking to do a direct migration, actually looking to do it in 2 steps and manually move the mailboxes(bypassing the EX2003 server step), would like to put the Ex2007 in its own child domain to bypass some other legacy issues, but would like to do it as painlessly as possible. We are just concerned about how putting the new 2007 server in its own child domain will impact the parent domain if we are pulling the users from that parent domain.Thanks,

For a starter, Exchange 5.5 knows nothing about Active Directory (and Exchange 2000 and higher), and Active Directory knows nothing about Exchange 5.5. They have their own totally independent directory services. In this manner Exchange 5.5 behaves just like another foreign mail system, such as Domino Notes, and the introduction of Exchange 2007 should present no problem. Two complicating factors could be:(1) Active Directory Connectors (ADCs), particularly from AD to Exchange 5.5(2) Outlook 2007 clients with Autodiscover that automatically may be configured to use Exchange 2007 I have no experience with your scenario, that is: I encountered something similar twice with Exchange 5.5 and Exchange 2000 without any issues. The Exchange 5.5 servers were part of the same forest as Exchange 2000. In the first case no ADCs were used, in the second case an ADC for populating AD was implemented at a later stage. MCTS: Messaging | MCSE: S+M | Small Business Specialist

Exchange 2007 is a forest wide application. So, if you have Exchange 5.5 in one child domain and 2007 in another child domain you are bound to have issues.If you are able to use ExMerge to export the mailboxes you will need to cross reference those exported PST files to the 2007 mailboxes. This may be trickey depending on the PST format created by Exmerge but I believe it would work.As a failback I would deploy one Exchange 2003 server in the AD environment prior to deploying Exchange 2007. This can then be used as a hop if you need it. If you deploy 2007 first and then try to deploy 2003 it won't work. SF - MCITP:EMA, MCTS: Exchange 2010, Exchange 2007, MOSS 2007, OCS 2007 -- http://www.scottfeltmann.com

Scott Feltmann: Exchange 2007 is a forest wide application. So, if you have Exchange 5.5 in one child domain and 2007 in another child domain you are bound to have issues. But Exchange 5.5 is not a forest-wide application without ADCs. The forest -- and this includes Exchange 2007 -- has no knowledge of Exchange 5.5, and Exchange has no knowledge of the forest. In this scenario Exchange 5 / 5.5 can even span multiple forests, as it did in the past (NT 3.51/ 4 domains and Windows 2000 forests). As said above, I was involved in two such projects with Exchange 5/5.5 and Exchange 2000. Exchange 2007 should behave no different. Already at that time I wouldn't have done it that way, and at this point I highly agree with you, Scott, I wouldn't do it this way today either. But we had no issues, whatsoever. And it isn't quite obvious, why we should.I would go from Exchange 5.5 to Exchange 2003 to Exchange 2007. There is a lot of documentation on the Net on how to do this, and this is supported by Microsoft.The Exchange 5.5 ExMerge .PST files are in ANSI format and have a size limit of 2GB. While I have not tested this with Exchange 2007, I have made imports from these files to Exchange 2000 / 2003.MCTS: Messaging | MCSE: S+M | Small Business Specialist

When talking about domains and subdomains, I assume that it is AD domains all in the same forest or are we talking about different forests or maybe SMTP domains.lasse at humandata dot se, http://anewmessagehasarrived.blogspot.com