As far as I can find there is no property on a `MailItem` one can access to discover if a `MailItem` is a draft.

One could check `MailItem.Categories` and see if it includes `Drafts` but this seems insufficient because:

Drafts don't have to be stored in the `Drafts` folder, they can be dragged and dropped into other folders.

The fact that a draft email retains its draftyness even if moved out of the Drafts folder indicates there must be some other way in which a `MailItem` is marked as a draft, but I haven't been able to find it.

Suggestions?