After you apply a retention policy to a mailbox, you can either wait for the next scheduled run of the MFA or start it manually so that the new policy is applied immediately. When the MFA runs, it performs the following tasks:
It applies the tags specified in retention policies to the mailboxes covered by these policies and stamps the items in the various folders covered by the policies with the appropriate tag name and expiration date.
It populates new managed folders into mailboxes that are under the control of a managed folder policy.
If a policy defines a retention or expiry period for items, it stamps a Messaging Application Programming Interface (MAPI) property (ElcMoveDate) on ...