Numerous error messages in the log

I find a large number of error messages in logging. I cannot assign these.

Examples:

ServiceException
IMAP error synchronizing account 11: Authentication failed.
Could not load account mailboxes: IMAP error synchronizing account 11: Authentication failed.

No iMIP messages to process.

Account 9 does not have an snooze mailbox

Account 12 does not have an archive mailbox

I also can’t see anywhere which account is meant by e.g. “Account 8”.

Can anyone explain how I can track down these errors?

Nextcloud-Server Version 28.02
Nextcloud Mail 3.5.5

Many thanks!