Like the Title says, Can you uninstall Exchange 2013 and install Exchange 2010 SP3 instead on Server 2012? If yes is there a procedure or is it even possible? would you have to do a fresh install of Server 2012? The story is that we have a new client and they had there previous IT company go in and install 2 servers with 2012 on them. Then the IT company went to install Exchange 2010 and realized that it wasn't compatible at the time with Server 2012, they then installed Exchange 2013 on the second server in trial mode as my client hadn't brought a exchange 2013 licences or CALs. they then set the first server up to be the DC. So I have been handed this mess. and any advice you guys n gals can give me would be very much appreciated.

Since Exchange 2010 was never installed and Exchange 2013 now is installed the answer is no. It's not supported to install an older version of Exchange if it has never been installed or complety removed. I wrote a blog about this regarding Exchange 2007 to 2010, it's available here: http://mailmaster.se/blog/?p=477 Magnus Bjrk mailmaster.se/blog

Thanks for your quick answer! Just to clarify even tho 2013 is installed on the second server could i blitz that server, reinstall server 2012 and then install 2010 with sp3 or wouldn't mix with the AD on the first PDC? many thanks for your help so far

It wouldnt be supported & will probably fail as the schema would have preped for exch 2013. There's probably an Exch Org already setup right.Sukh

Thanks for your help!! I'll submit these answers to our client and see what happens next.

Hi DarrenUTSI Any result for those answers Cheers Zi Feng TechNet Community Support