Erroneous outbox message fails repeatedly

Steps to reproduce

1. Compose and send a message
2. Run into https://github.com/nextcloud/mail/issues/8165, or likely other sending errors
3. Look at the outbox

Expected behavior

The message is attempted to be sent once, then shows as failed

\OCA\Mail\Service\OutboxService::sendMessage should mark the message as failed

Actual behavior

The message is attempted to be sent with each cron job, e.g. every 5mins.

+------------+--------------+------------+--------+
| account_id | user_id      | send_at    | failed |
+------------+--------------+------------+--------+
|        123 | christoph    | 1677236522 |      0 |
|        123 | christoph    | 1677237015 |      0 |
|        123 | christoph    | 1677237164 |      0 |
|        123 | christoph    | 1677237299 |      0 |
|        123 | christoph    | 1677237430 |      0 |
|        123 | christoph    | 1677237455 |      0 |
|        123 | christoph    | 1677612832 |      0 |
+------------+--------------+------------+--------+

Mail app version

3.0

Mailserver or service

No response

Operating system

No response

PHP engine version

None

Web server

None

Database

None

Additional info

No response

Start with OCA\Mail\Service\OutboxService::sendMessage and trace how an unsuccessful send is handled during cron processing. Reproduce the failure described in the issue and verify that the outbox record is marked failed after the first attempt, so later cron jobs do not retry it.