Email Passed checks even though DNS server or domain failure RSS

1

Hello,

I'm looking at the ORF viewer and see the following Message for one of the incoming messages:

DNS error. Test: "DNSBL: AHBL", server: "4.2.2.3", domain: "188.192.236.23.dnsbl.ahbl.org", record type: A, protocol: UDP. Server response: DNS server or domain failure (SERVFAIL, RCODE 2).

The message is spam and I think this DNS error suggests that the domain is not found. The question is why then the message gets passed to the recipient and doesn't get marked as blacklisted?

Thank you,
Serge

by sergela 4 years ago
2

@sergela: Hello,

This message reports that looking up 188.192.236.23.dnsbl.ahbl.org in DNS has failed. These type of errors are actually expected, so the error handling policy of ORF is to skip the smallest possible step in the testing process on a blacklisting error. In this particular case, it means that the email testing continued with the next DNSBL, barely affecting the overall performance. Due to this, a single DNS failure will not automatically cause the email to pass checks.

The reason why this lookup has failed is that the AHBL blacklist has shut down a while ago. I recommend updating your DNSBL and SURBL definitions from http://vamsoft.com/support/docs/knowledge-base/update-dnsbl-surbl and to enable the recommended DNS Blacklists and SURBLs from here: http://vamsoft.com/support/docs/knowledge-base/recommended-dnsbls-surbls-agents.

Also, I have noticed that the DNS server from the log message is 4.2.2.3, a Level3 DNS server. We recommend setting up ORF with a dedicated local DNS server using root hints as you may run into issues with DNS servers that aggregate traffic from several clients. Please see http://vamsoft.com/support/docs/how-tos/best-practices-5.3#bp-get-dns-right regarding this.

by Péter Karsai (Vamsoft) 4 years ago
(in reply to this post)

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