I believe that Exchange uses the newer of the message creation date or the message update date.
From: [email protected] [mailto:[email protected]] On Behalf Of N Parr Sent: Monday, February 22, 2016 12:46 PM To: [email protected] Subject: [Exchange] Archiving with 2013 We are migrating domains and doing cross domain migrations. Archiving for users is turned on for mail over 120 days on the destination domain. The destination mailboxes are being created at the time of migration. My Googlefu is failing on me because there’s so much terminology around this. How does Exchange treat the mail that is migrated? Does it see all the mail as less than 120 days or does it start migrating mail out of the account like normal? If so does it take some time, assume we haven’t made any changes around the default schedules. I am seeing some users archiving being populated but after many days it’s just a trickle and not consistent. Thanks
