Nextcloud AIO vs mailcow Snappymail works, mailapp fails


In this topic I got the mail app working for the first time (Nextcloud mail docker dovecot).
3 month ago it stopped working and now I partially got it working again, here’s my problem description:

I am running Nextcloud AIO and Mailcow, mailcow is up to date, Nextcloud is still on 28 (awaiting the normal upgrade to 29).

Both are running in their own docker network, so I had to give Mailcow double network adresses for the services used by Nextcloud mail, Dovecot and Postfix and allow the Nextcloud network to connect to the services. The adresses got lost 2 month ago (I suspect) In a container upgrade since the last time and this is how I got it working again, at least somehow.

I am able to connect Snappymail over IMAP to dovecot and I am also able to connect to postfix, shown in the logging of Postfix.

I am able to connect Nextcloud Mail over IMAP to Dovecot, but Postfix only mentions chunking, Nextcloud log only mentions “Server requires Authentication”.

Using the mail app horde Imap client exceptions are logged as well as allowed memory size exhausted loggings.

When enabling debugging (debug on and loglevel 0 in config.php) no extra logs are created, aside the nextcloud.log, so no trail can be found of why the mail app is failing to authenticate.

In Snappy mail under domains I configured exactly the same settings (servername, port authentication protocol) as I did in the mailapp regarding IMAP and SMTP.

How to troubleshoot this, or how to reset the mailapp fully (remove app and settings and reinstall / reconfigure)?

Thanks again for your thoughts!

After re-enabling the mail app.

I think all mail-app related database items need to be removed, snappymail is very snappy at the same time.

Is this the wrong place to ask about the Mailapp?