Hi @Innocent Heartvoice ,
Exchange 2010 is supported with Windows Server 2012 R2 AD servers and AD forest functional level of 2012 R2, as long as your Exchange 2010 is running SP3 RU5 - RU21.
There shouldn't be any effect on your Exchange when upgrading your AD forest functional level to 2012 R2.
For more information, see:
Exchange Server supportability matrix
https://learn.microsoft.com/en-us/Exchange/plan-and-deploy/supportability-matrix?redirectedfrom=MSDN&view=exchserver-2019
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Best regards,
Leon
Hello @Innocent Heartvoice ,
I'm just following up to make sure you received my last reply and that my answers properly address your questions. If you have any further questions or concerns about this post, please let us know.
Best Regards,
Daisy Zhou
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