messages with misspelled email addresses are stuck in outbox and cannot be sent again

Steps to reproduce

1. Create a new message
2. Write a message and, for the recipient use a nonexisting email address like "test"
3. Send the message
4. After you get the notification that the message cannot be sent, go to the outbox and replace the email address with a working one
5. Send the message again

Expected behavior

Sending process should work.

Actual behavior

Sending process fails with the protocol entry: "Could not send message because a previous send operation produced an unclear sent state."

Mail app version

5.0.7

Nextcloud version

31.0.5

Mailserver or service

all

Operating system

Ubuntu 22.04

PHP engine version

PHP 8.3

Nextcloud memory caching

No response

Web server

Apache (supported)

Database

MariaDB

Additional info

This is a very common scenario since it's rather easy to misspell an address. The only way to correct that is to copy the content from the old message, delete it from outbox, recreate it, and paste the content.

Start by reproducing the failed send, then trace the outbox retry flow and the handling of the protocol entry "Could not send message because a previous send operation produced an unclear sent state." Done means correcting the recipient in an outbox message allows it to be sent successfully without recreating the message.