Service’s zone: dnsbl.spfbl.net
This service cannot be used for rejection purposes during the SMTP transaction. It can be used in scoring systems such as Spamassassin or Rpamd to have the message delivered to the recipient’s Junk folder. The responsible for the receiving system, who is consuming this service, shall be responsible for non-compliance with this rule. The SPFBL.net will not be responsible for the misuse of this service.
It is noteworthy that, in the case of returning 127.0.0.4, we flag all IPs which we consider unsuitable for hosting mail transfer agents. In that case, the DNSBL does not only list systems that send spam, so it’s up to each administrator to decide how to use it. Making an analogy with the RFC Ignorant list (now RFC Clueless), we also require a number of important settings, so we could be called the “SPF ignorant” or “FCrDNS ignorant” system. In addition, any machine with no purpose of email service is a potential vector of a hacker attack, so this flagging also prevents any possible attack rather than waiting for the first damage to blacklist the IP after the injury caused. More about our rules, in the our delist page. Contact us to know how to report SPAM in our platform and then force the sender stop it.
IMPORTANT: We do not provide any guarantees, despite the best efforts to maintain a stable and coherent system. Use at your own risk and take into consideration that our systems works based on reputation, without privileges to any system, including Internet providers and email marketing systems, if they have a poor reputation. For this reason, our DNSBL can not be used for message rejection, but only to forward the message to the recipient’s Junk folder. Check your MTA documentation for details or, if it is not feasible, consider use SpamAssassin or Rpamd.
IMPORTANT: Current limit is 10 queries per second and the response will have rcode 5 (REFUSED) when reached. Higher frequencies require contribution. Please contact us informing your IP or range, for further details. Even within the query threshold, consider making a donation so we can maintain and expand our free services. If your Unbound resolver are having query limit issues, try to set its parameter qname-minimisation to value “yes”.