In Exchange 2010, you can provision Personal Archives for your users. A personal archive, or an archive mailbox, is an additional mailbox where users can move older messages or messages that they don’t need to access frequently but may still want to retain for a longer period. You can also apply a Retention Policy to mailboxes to have old email moved to the archive after a certain period. Moving older email out of the primary mailbox keeps it smaller and faster, although larger mailboxes aren’t a concern according to Microsoft’s design goals for Exchange 2010 and its large mailbox vision, which emphasizes large mailboxes (10s of Gigs) at a low cost, with great performance and high availability.

In Exchange 2010 RTM, the only option to provision an archive was on the same mailbox database (MDB) where the user’s primary mailbox resided. In Exchange 2010 SP1, these choices widen significantly. You can create (or move) a user’s archive mailbox: