The draft folder that's associated with each mailbox currently has the exact same behavior as other folders like inbox.
However, this paradigm doesn't really make sense for the drafts folder in my opinion, so I wanted to propose my thoughts and seek feedback here.
The draft folder should always show the count of all messages, and the read and unread statuses should not apply to draft messages.
The rational is that in the inbox, the relevant statuses are read and unread, because the goal is to read the messages. Reading a message decrements the total count, because the goal was completed for that message.
However, for drafts, the goal is not to read a message, it's to send a message. So the status and count shouldn't change until a draft has actually been sent, not just read.
It's a little tedious that I have to mark my drafts as unread whenever I go back to review pending messages or want to proofread them, but am not ready to send them yet.