I am going to upgrade an exchange 2013 CU to CU 23, right now there is an exchange server 2007 in the environment but the services have been disabled, it is technically not alive.
I have done testing in my own environment with the 2 of the DC's (Virtual) and did the upgrade of Exchange server (virtual) which completed successfully. But wondering if I can expect any gotcha's when I do this with the third DC which is running exchange 2007 added back
