@neki The misconfiguration warning is for your IP and has no relevance for incoming mails. That warning is being shown because Spamhaus is not reponding correctly to the request from Cloudron and Cloudron is incorrectly interpreting that as your IP being blocklisted. It is nothing more than a display error though and should be fixed in the next release.
If you are seeing incoming mails rejected due to Spamhaus listing then this is due to the DNSBL checking. The error may well be with Cloudron and how Spamhaus reports are interpreted, but that will be resolved if you deactivate the checks.
@SansGuidon Had you removed Spamhaus from the DNSBL checks? I think the issue is (at least partly) to do with changes in the way Spamhaus processes queries (I noticed a lot of errors in the logs before deactivating Spamhaus altogether) and the way Cloudron interprets the results when errors are thrown.
I have two Cloudron servers, both running version 8.3.2, but one on Ubuntu 22.04, the other on Ubuntu 24.04. Interestingly, the server running on 24.04 does not show the (false) email configuration error, but the one on 22.04. regularly does. As already mentioned, however, that is just an icorrect message and has no affect at all on deliverability as that will depend only on the receiving mailserver.