Here's the timeline:
June 16, I installed a new exchange server. It's a VM running in Hyper-V on Server 08, R2.
July 13, there's a power outage (massive) and the physical host, and of course all of the VMs, go down ungracefully.
July 13, everything is back up EXCEPT, in Hyper-V, the exchange server is missing. I created a new VM, pointed to my Exchange VHD, and spun it back up. Mail was flowing.
Aug 20, the Exchange VM mysteriously goes away! We create another new VM, point to the Exchange vhd, and we are back up.
I learn that I had AV installed on the physical and that the AV was scanning my xml and vhd files and interpreting the xml as "virus-like and quarantining them. So, I exclude xml and vhd files from AV scan and get my exchange server back up.
Here’s the mystery…
For every user, the user is missing emails for July 13 thru Aug 6. Now remember the power outage started on July 13, so that data sort of makes sense, but the next outage was on Aug 20. Still, I have verified that there is no mail for July 13, thru Aug 6. No sent mail, no received mail, no deleted mail for those dates.
There is only one VHD so I know I didn’t attach the wrong one.
Mail flowed fully from July 13 until Aug 20, but on the 7/13 thru 8/6 email is missing.