Using New Outlook on Windows for personal email, calendar, and contact management
Of note, this worked for me - thank you!!
The specific scenario which got the message stuck:
- Opened an email that had another email on it as an attachment.
- Opened the attached email
- Tried to reply to that email (I know, not normally something done but in this scenario it made sense)
- Sent the reply, and it got stuck in that folder as, "queued"
I do think in reading this that there are other scenarios where message get stuck in the Outbox.