SpamHaus false positive on Ubuntu 24.04 + latest Cloudron

[archos]

Hi,
Cloudron UI reports my IP as listed on SpamHaus, but check.spamhaus.org shows no issues for my hostname.
If I’m not mistaken, this was already addressed in an older release. I’m on Ubuntu 24.04 with the latest version of Cloudron.
The impact is real – some mail servers are rejecting outbound mail from my server with error 554 5.7.1. MX, DKIM, SPF, DMARC and PTR records are all green.
Is anyone else experiencing this on Ubuntu 24.04 + latest Cloudron? Thanks.

[joseph]

Is the IPv4 check failing or the IPv6 check?

[archos]

Both today – sometimes it’s just one, sometimes both.​​​​​​​​​​​​​​​​

[archos]

After further investigation it seems that this is not a Cloudron bug, but an actual listing of the server IP on a blacklist.

I checked the mail server logs on the Cloudron host in:

/home/yellowtent/platformdata/logs/mail/app.log
/home/yellowtent/platformdata/logs/mail/app.log.1

I do not see any signs of a compromised server or bulk spam activity. The logs mainly contain normal system notifications and failed SMTP authentication attempts from random internet bots.

At the moment I do not see any evidence that the server is compromised or that it is sending spam.

Is it possible that I am looking in the wrong place? Are there any other Cloudron logs related to outgoing mail or postfix that I should check?

[joseph]

@archos check the DNSBL response code. Each response code has a meaning. See https://www.spamhaus.org/faqs/dnsbl-usage/#200 inside search for "Return codes". I cannot see how to deep link or even select the question in that page.

[archos]

Small update from my side.

I contacted Spamhaus through their ticket system and after communicating with them it seems everything is now resolved and the IP has been removed from the blacklist. Emails are working normally again.

Sorry for the false alarm and thank you for your help and responses. I did notice that occasionally I still see the error that was present in the previous version, so I will keep