After you migrate a mailbox, the old mailbox may receive mail that was in transit. Some systems can forward mail or reply to the mail with the new address. If your existing system doesn't have these features, have users periodically connect to their old mailboxes, or use the source extractor and the Migration Wizard to forward the mail. For more information, see the chapter pertaining to your existing system later in this guide.
When a user replies to a migrated message, there are three possible results:
|A display name matches the display name in the message||The address is resolved.|
|More than one display name matches the display name in the message||The user is presented with a list of choices.|
|No display name matches the display name in the message||The user needs to find the new address in the list.|
For a user to be able to reply to the migrated message, you must have all names in the Microsoft Exchange Server address list, either as custom recipient addresses for users on the existing system or as mailboxes for users on the new system, but not as both. Any mail moved from your existing system contains the sender's and recipients' display names.