I restored a storage group on Exchange Server 2007 Sp1 Rollup 6. I have attempted to merge one of the restorered mailboxes to an empty mailbox via the Exchange Toolbox. When I do this I receive the following error Moving messages. Failed to copy messages to the destination mailbox store with error: An unknown error has occurred., error code: -1056749164. Via google I found out this is a know error message that has do with a mailbox that has over 5,000 items and was fixed in Rollup 8 for SP1. I decided to update to SP2 and tested again. Same error. I tried restoring other mailboxes with less than 5,000 items to the same mailbox with succes. I am at loss. Any help would be greatlly appreciated.