Exchange has a number of features that are broken once you use EXMERGE to move you email data from one Exchange server to another. It helps to understand which features will no longer function an potential workarounds prior to the event, rather than after you ve moved the data.
1. Single Instance Storage
2. Group Appointments links – if you try to update a meeting, you will get a Non Deliverable Report back from the system.
3. Assigned tasks if you try to update the status of a task, you will get a Non Deliverable Report back from the system.
4. Return email addresses (internal or GAL listed ones) if you respond to an email that was sent internally to you before the upgrade you will get a Non Deliverable Report back from the system. If however before you send the message you retype the recipients name, it will autoresolve to their new email address and work.
5. Journal Links will also not be linked back to the original contact you can relink manually, but this can be a long process.