AHBL Blacklist Closed
We use Spamassin and Amavis to keep control of spam being sent to our users.
These use blacklist services to help determine if a message is a spam. The blacklists keep a list of servers that are known to regularly send SPAM. If the sending server gives a positive match on a black list it is very likely that the message is spam.
One of the blacklists that we use is AHBL, which seems to have closed down. This means that the anti-spam software thinks that all mail-servers are on the blacklist, and all messages have their spam score artificially raised and emails are much more likely to be marked as SPAM.
For spamassassin and amavis, you can check if your system has this issue by checking the headers of a message that you have received:
X-Spam-Status: No, score=3.5 required=6 tests=[BAYES_50=0.8,
DNS_FROM_AHBL_RHSBL=2.699, HTML_MESSAGE=0.001] autolearn=no
This is showing that AHBL is adding 2.699 to the spam score.
The way to resolve this is to update your spamassassin settings to set a score of 0 for DNS_FROM_AHBL_RHSBL.
For spamassassin, you need to update /etc/spamassassin/local.cf to add:
score DNS_FROM_AHBL_RHSBL 0
Finally, don’t forget to restart amavis / spamassassin