In the pass I had this problem read receipts are sent to users after shortcut deletion runs and removes an item that has not been read, I solve with the HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\KVS\Enterprise Vault\Agents\ (Dword:ClearUnreadNotification=1). Then we upgrade Exchange to 2010, and then it start sending this read receipts again when but now was when the message was archive, we stop archive unread message.
Yesterday people started reclaim again, I check, we are not archive unread message, and the read receipts refer to expiring shortcut, and I check the Registry Entry is set to 1.
Please help? I'm Lost
Without reproducing it all, I don't know.
You could search though for the name of the key, or, 'unread', that sort of thing.
I cant recreate the issue, bur I'm almost certain that this occur because I have SingleItemRecoveryEnabled enable for all mailbox, and when dumpster expire this receipt are send.