Some (not all) spam emails are not detected by the DNSBL filter.
In the hMailServer log I can see:
DNS lookup: 188.8.131.52.zen.spamhau
s.org, 0 addresses found: (none), Match: False
But, if I try to execute the following command:
it does return a match:
s.org has address 127.0.0.3
The hMailServer's spamhaus entry is configured as follows:
<DNSBlackList Name="zen.spamhaus.org" Score="3" RejectMessage="Rejected by Spamhaus." Active="1" ExpectedResult="127.0.0.2-7"/>
We are using local Windows Server DNS service for caching and I can't find the missed DNS requests in the cache.
How that could be fixed?