One drafts folder for every mailbox you can see, not one per mailbox.
Every email you start and don't send lands in one place, Drafts, in My work, regardless of which mailbox you were writing from.
Select Drafts to see everything you've started. Select a draft to reopen the composer exactly where you left it, then finish it and send it, or discard it.
Two drafts waiting to be finished, from two different mailboxes, in one list.
