Messages stuck in outbox

I had messages stuck sitting in the outbox.
I can see that no attempt is made by k9 to reach my mail server when I click send or restart the android device.
I can send new messages w/k9 and they’ll briefly appear in the outbox above the old messages and then be immediately sent and removed but the old messages remain. So sending works.
Only way to get the old messages to send was to move them to drafts and click send from there. They then go out immediately.