Hello, I am about to carry out some work and just want to clarify if it will achieve what I want and there will no adverse effects. Here is my scenario: Parent domain - server2008r2 dc x 2 - Exchange 2007 x 1 (this is the live production environment) child domain - server2012 dc x 1 - server 2012 member ready for exchange 2013 (this domain is for testing only) I have setup a child domain for use by testers in my organisation, both domains are on the same subnet and are at the same site. DNS is working perfectly between the two and the DHCP servers are in the parent domain, along with WSUS, AV and most of our role servers. Our testers need an exchange server for their testing VMs to use, I am about to install Exchange 2013 on a server in the child domain. How will this effect Exchange/Email in the parent domain? Ideally I want the child domain email to be completely separate from the parent. I know the installation will upgrade the forest schema so will that also have any adverse effects? Cheers in advance!

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Hi Ben, Firstly, it is not supported to coexist Exchange 2007 with Exchange 2013 until Exchange 2013 CU1, which is scheduled to be released in Q1 2013. (http://blogs.technet.com/b/exchange/archive/2013/02/12/released-update-rollup-6-for-exchange-server-2010-sp2-and-exchange-2007-sp3-ru10.aspx) Even you can introduce Exchange 2013 into Exchange 2007 environment, there might be some unknown issues for coexistence and you are not able to migrate from Exchange 2007 to Exchange 2013. For test purpose, we usually recommend to install Exchange 2013 into a separate domain. So that, it will not impact your product environment. Thanks, Da Xu

Hi Ben, Firstly, it is not supported to coexist Exchange 2007 with Exchange 2013 until Exchange 2013 CU1, which is scheduled to be released in Q1 2013. (http://blogs.technet.com/b/exchange/archive/2013/02/12/released-update-rollup-6-for-exchange-server-2010-sp2-and-exchange-2007-sp3-ru10.aspx) Even you can introduce Exchange 2013 into Exchange 2007 environment, there might be some unknown issues for coexistence and you are not able to migrate from Exchange 2007 to Exchange 2013. For test purpose, we usually recommend to install Exchange 2013 into a separate domain. So that, it will not impact your product environment. Thanks, Da Xu

Thanks for your time guys :) I was working on this at home last night using Hyper V to see how things go and had some issues actually getting my organisation prepped. I learnt that I cannot upgrade the forest schema by running the setup on a child domain server even when logged on as enterprise admin. So I ran it from a 2012 Member in the parent and the schema upgraded successfully, however for some yet unknown reason my replication then let me down and the child DC did not pickup the new schema (exchange security groups etc). So I could not continue to setup ex13 in the child. So would you recommend just creating an entirely separate forest for testing and creating a trust?

Hi Ben, Actually, I mean you should wait for Exchange 2013 CU1. After that, it is supported to deploy Exchange 2013 into Exchange 2007 environment. Before that, the Exchange 2013 should be installed in a stand alone domain for test purpose. Thanks, Da Xu

Hi Ben, Actually, I mean you should wait for Exchange 2013 CU1. After that, it is supported to deploy Exchange 2013 into Exchange 2007 environment. Before that, the Exchange 2013 should be installed in a stand alone domain for test purpose. Thanks, Da Xu