I had this question after viewing How can I remove all references of an Exchange 2003 server from an Exchange 2007 organization?
I am trying to erase/remove references to 2 old Exchange 2007 servers in an Exchange 2010 environment. While trying to install a new 2016 Exchange server, I am stopped at PrepareSchema with a warning that all 2007 Exchange servers must be upgraded to 2010 SP3. These are the long deleted Exchange servers which obviously no longer play a role in Email functionality. I have no recovery options of the old 2007 instances. Also when I run ADSIEDIT I do not have the same key structure (no services folder hence, no exchange folder) that I see referenced in the Exchange 2003 solution. Any help is appreciated.