The Abusix Policy Blocklist is a policy-based blacklist containing IP addresses that should not connect directly to external SMTP servers and should instead use their provider's smarthost for relaying messages.
The Abusix Policy Blocklist is a specific type of IP-based blacklist that contains a list of IP addresses that should not be connecting directly to external SMTP servers. It is operated on the DNS zone dynamic.mail.abusix.zone. The purpose of this list is to preemptively identify any IP address that is unsuitable for sending email directly, helping to catch threats like newly compromised hosts or hijacked IP space without needing to wait for spam reports.
This blocklist is built by continuously scanning the entire IPv4 range and applying a strict policy. An IP address will be listed on this blacklist if it fails to meet certain criteria. The policy is primarily focused on Reverse DNS (rDNS) records. Key listing criteria include:
When an IP is queried against this blocklist, specific return codes indicate the reason for the listing. A return code of 127.0.0.11 means the host has a generic rDNS, while 127.0.0.12 means the host has no rDNS at all. It is important to note that it is normal for non-SMTP server IPs to be on this list; this will not cause any negative effects for services other than email.
The Abusix Policy Blocklist is run by Abusix, a company specializing in network abuse management, email security, and threat intelligence. Abusix provides comprehensive solutions designed to protect networks and improve internet security.
The company's focus is on stopping threats before they reach end-users by targeting the most common vectors for cyberattacks, such as email and network traffic. They offer proactive security solutions that serve as a first line of defense, blocking a high percentage of email-based threats and helping organizations manage network abuse effectively.
Removing your IP from the Abusix Policy Blocklist (blacklist) is a straightforward process. Before you begin, you must fix the underlying issue. Since this is a policy blocklist, the problem is almost always related to the IP's rDNS configuration. Ensure your IP address has a unique, non-generic rDNS record that reflects the hostname of the sending server.
Once you have corrected the rDNS issue, you can request delisting. Anyone can request removal, and a semi-permanent exception will be created. You can start the process by visiting the Abusix Lookup and Delisting page. You will need to create a free account to submit a delisting request; this is required to prevent anonymous abuse of the system. Follow the instructions in the user portal to remove your IP. Note that you can only delist single IP addresses, not entire CIDR ranges.
Delisting requests are processed immediately. The change will reflect in DNS queries instantly, but it may take up to five minutes for the removal to propagate to customers who use rsync to get the blacklist data.
The impact of being listed on the Abusix Policy Blocklist is medium. This blacklist is used by organizations as a first-line defense on their border SMTP hosts to reject connections from IPs that do not meet standard internet policies for mail servers. If your IP address is on this list, your emails will be blocked by any mail server that uses this specific blocklist.
However, the impact is targeted. Abusix warns that this zone should only be used to check the IP address that is handing off the email to the mail server. It should not be used to check IPs in 'Received' headers or on smart hosts, as this can cause a significant number of false positives. This means that while a listing can cause delivery failures, its use is more specific than a traditional spam-based blacklist.
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