The JustSpam Blacklist is a low-impact IP blocklist that identifies the worst spam offenders by only listing IPs that are already present on other prominent blacklists, making it a safe option for outright blocking.
The JustSpam Blacklist is a DNS-based Blocklist (DNSBL) that lists IP addresses believed to be sources of spam. Its technical designation is dnsbl.justspam.org. It is designed to only list the most definitive spam sources, what it refers to as the "worst offenders", to provide a high-confidence data source for filtering email.
This blocklist (or blacklist) operates with a strict listing policy to prevent false positives. An IP address is only added if it meets two conditions: it is observed sending spam from an IP that has never sent legitimate email to their systems, and it is already listed on at least one other well-known, independent blacklist. This dual-check mechanism is central to its goal of accuracy.
Due to its policy of listing only high-confidence spam sources, the maintainers recommend using the JustSpam Blacklist for outright blocking of mail. They advise against using it in a scoring system, as a listing should be treated as a definitive signal rather than a weighted indicator.
The JustSpam Blacklist is operated by the JustSpam organization. The project was founded on the belief that while spam remains a major problem, many existing blacklists carry a significant risk of blocking legitimate emails. Their goal is to provide a more reliable, first-class email reputation system.
A core principle of the project is that the service is completely free of charge. This applies to both commercial and non-commercial use of the blacklist data, and importantly, the process for requesting removal is also free. The JustSpam blacklist has been available to the public since late 2011.
Removal from the JustSpam Blacklist is a self-service process, but it requires critical prerequisite steps. Before you can request delisting, you must ensure your IP address is no longer a source of spam and is not listed on other major blocklists.
Follow these steps to request removal:
Warning: If an IP address is removed and then gets listed again, it will be blocked from using the self-service removal tool for the next 30 days. Ensure your systems are secure before requesting delisting.
The direct impact of a listing on the JustSpam Blacklist is considered low. This is a direct result of its listing methodology.
Because an IP must already be on another major blocklist to be added here, the primary email deliverability issues will originate from those other listings. Any mail server using the JustSpam Blacklist is likely using other data sources that would have already flagged your IP. Therefore, a listing here is more of a symptom of a wider reputation problem than a root cause.
Your priority should be to identify and resolve all other blacklist listings. Doing so will not only solve the main deliverability problem but is also a mandatory step to becoming eligible for removal from this one.
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