Marking unregistered mail as read or unread

In the Unregistered Mailbox, there are columns for Read/Unread status and Date Read. You can change an item’s read/unread status by selecting an item, and then selecting More > Mark as Read or Mark as Unread.

For existing items, any processed items are shown as read, and the Date Read column populates with the processed date. Unprocessed items are shown as unread.