I inherited a small network that is currently running two Windows 2008 R2 domain controllers and single Exchange 2010 server for our mail. Everything seems to be working as it should, however I have seen references to a previous exchange server in the Exchange application log, mostly related to a default address book issue. I really want to migrate our DCs to 2012 R2, however digging around Exchange, I'm finding more pieces to the previous exchange server which was 2003. Sure enough (Get-ExchangeServer | Format-List) shows two servers. EX and EX1. The old server no longer exists and was deleted long ago. How can I now remove these references without disrupting our current server? Also, since that is a 2003 exchange that was installed, is there a danger by migrating to Windows 2012 R2 - since it is surely not supported? Again, I haven't noticed any issues with our current Exchange server, other than a stray reference to the old server in the application logs.