With the 
Patch
Exchange References batch job, you can ensure that when you
have upgraded the Exchange server or applied a new service pack or
hotfix, the mail entries are assigned new primary keys. The batch
job identifies all the mail items in the storage folder, finds the
attachment record and adjusts the reference from the attachment to
the mail item.
You can also use this batch job if you move the storage folder from one folder to another. To do this, create a new storage folder, change the setup to match this folder and move all the messages to the new folder. When you run the batch job, all the links are updated to reflect the new location.
Click OK to start the batch job. If you do not want to run the batch job now, click Cancel to close the window.