Outlook Read receipts not automatically moved to Deleted Items

Hi all,

One of the users usually sets all read receipts to Deleted Items after processing. I have been examined Tracking Options where “After processing, move receipts to” was checked. The problem comes when the read receipts are only targeting to external parties while internal ones work perfectly fine (all moved to Deleted Items). Now he has tons of read receipts in his Inbox.

Can anyone give help on this issue? Thanks much!

Regards,
Suzanne