[IMAP] Mark deleted messages created by auto-save as read

If auto-save is enabled for messages that are being composed using an IMAP account, a different version of the message is saved every time auto-save is performed. When the message is finally sent, all the “intermediate auto-saved versions” are moved to Trash, but they are marked as unread. Why?

This behaviour concerns Gmail IMAP, but I believe the same happens also in case of other IMAP accounts (unfortunately, I have no way of testing it on a plain-vanilla IMAP server).

Although it is not wrong per se, it unnecessarily grabs user’s attention and does not look good. Would it, please, be possible to mark any such “intermediate message” as read before moving it to the Trash folder?