Moving mailboxes, Exchange 2010 way

@Tom: So, we’d advise against simply doubling the number, as the load will actually be on the target server, not on the CAS. The number is mostly dictated by the mailbox average size. If most of them are small (<20Mb I’d say), they may be able to go as high as 20 (depending on how powerful their mailbox servers are). Again, CAS is the least of the worries here. CAS will only start to suffer if all moves have really large folder hierarchies (2000+ folders), in which case the memory pressure will build up. I’d say profiling and testing is the best option. It may be possible that during the initial phases of the migration the target servers can handle more simultaneous moves, and as more users start using their mailboxes on the target forest, the load available for moves will decrease, so they’ll have to throttle down.