I am completely baffled by this the more I look into it, and my VPS host has also checked a bit.
Spamhaus says the IP is ok, but messages are being returned:
Final-Recipient: RFC822; firstname.lastname@example.org
Remote-MTA: DNS; xxx.xxxxxxxxx.com
Diagnostic-Code: SMTP; 554 5.7.1 Service unavailable; Client host [xxxx:xxxx:xx::84] blocked using zen.spamhaus.org; https://www.spamhaus.org/sbl/query/SBLCSS
Last-Attempt-Date: Tue, 14 Feb 2023 06:11:06 -0500
I also added whitelist in SpamAssassin which doesn’t appear to be doing anything to help.
These are crontab emails through sendmail from 4 other servers, to me on my server. All for servers set up the same (but different cities same VPS provider). Only 1 are the emails going through correctly, the rest say being blocked by Spamhaus.
It’s just frustrating as it appears that MIAB says it is blocking them because of Spamhaus, but Spamhaus says those IP’s are not on any block lists. MIAB may be blocking for some other reason, but if so, it’s saying Spamhaus incorrectly if that is the case, and not giving the correct reason.
I’ve been looking everywhere I can think to look, but not really finding anything that is pointing to what the real issue is.