A method for mailbox migration includes creating a message ID map for the source and destination mailboxes, and storing the message ID map in a migration cache file that can also hold message ID persistence and message state indicator data. A precopy operation is performed while the source mailbox is...http://www.google.com.hk/patents/US7587455?utm_source=gb-gplus-share專利 US7587455 - Method for mailbox migration
