When you move a user from 2003 to 2010 they retain the 2003 style LegacyExchangeDN. This isn't normally a problem unless you have a program which references the LegacyExchangeDN in which case it tries to look under Exchange 2003 where the mailbox no longer exists and therefore the program can fail to find the mailbox (yes, some programs still reference the legacyExchangeDN to find the mailbox even in 2012).
NOTE: The migration for this current scenario has not yet taken place, but I have noticed it as a problem for some test users so need to do some planning.
- Is it best practice to add an X500 and replace the current legacyExchangeDN on all mailboxes moved from 2003 to 2010 just incase you hit the above style of problems? Or is this done automatically now under SP2 by any chance?
- Or do people just leave the legacyExchangeDN alone and fix people on a per-fix basis if they hit problems such as the above at a later date and add an X500 at that time
I am leaning towards just fixing all mailboxes with a 2010 style legacyExchangeDN and adding an X500 address to all migrated mailboxes once they move across (unless Exchange 2010 SP2 does this automatically for you these days?). I have an export of the original legacyExchangeDN values so it will be no problem creating an X500 address when it comes to moving users across.
Thoughts?