Does the modify date change when you move PST archives from Exchange 2003 to Exchange 2010?
We are about to conduct a migration from EX03 to EX10 within the same domain. We will be absorbing partial user PST archives into our data center and want to set a retention policy that keeps all emails going back 2 years.
We want to only import the last two years of email (back to Feb. 2012) and have the users keep the rest on their machines (BYOD).
Our concern is retention. I was told that Exchange 2010 goes off the modify date and that by importing the PST (or at least part of the PST) into Exchange, the modify date will be updated to today's date.
Question: Upon adding the PST file, will the modify date change for those emails?
If so, will Exchange delete/remove those emails all at one time two years from today's date or will it remove them based on when they were sent/received?