This issue occurs if either of the following conditions is true:
- The item that is being deleted no longer exists on your Exchange mailbox, or the item was already deleted from the mailbox.
- The Exchange server cannot delete the requested item.
You are seeing these emails because the Unread Mail folder also shows you emails from a system folder that is hidden from the left side of Outlook. Below are steps to remove the system folder emails from showing up in Unread Mail.
Step 1
Open Outlook.
Step 2
Go to "Search Folders" on the left column.
Step 3
Right click on the Unread Mail folder and choose Customize This Search Folder....
Step 4
Click Browse.
Step 5
Unselect the checkbox for your Mailbox (the top level mailbox folder).
Step 6
Manually check all the folders you would like to see unread mail from.
Step 7
Press OK.
Last modified: September 6, 2018