Mark all mail that will be deleted on expiration with "EXPIRE" MailType
I rely heavily on using my Inbox as a means of storage for many items and materials. Currently, while looking at the Inbox list, I do not see a way to determine whether or not an entry will be returned to the sender or deleted after the expiration. It would be really nice if you could open your inbox and instantly identify which items need your attention, and which ones will be safely returned to sender.
I've made local changes to do this for myself, and it worked out well so I'm suggesting it here officially.
In MailTracking.lua, I modified the private.GetMailType function to check if wasReturned is true. If yes, I return the "EXPIRE" type. I went with this approach over making a new type because it hooks nicely into the "open all expires" button already there.