The UCEPROTECT DNSBL Level 3 is a highly aggressive IP blacklist that lists entire Autonomous Systems (ASNs) containing a significant number of spam sources, and due to its broad scope, this blocklist generally has a low impact on deliverability.
UCEPROTECT DNSBL Level 3 is the most severe of a three-tiered blocklist system. Unlike other blacklists that target individual IP addresses, Level 3 lists entire Autonomous Systems (AS). An AS is a large network, typically operated by an Internet Service Provider (ISP), a hosting company, or a large corporation. A listing on this DNSBL (DNS blacklist) occurs when an excessive number of IP addresses within that AS are found to be sources of spam, leading to listings on UCEPROTECT's Level 2 blocklist.
The policy behind this approach is aggressive and intentional. UCEPROTECT's goal is to compel providers and carriers to enforce better security and anti-abuse policies across their networks. By blacklisting an entire provider, they create pressure from all of that provider's customers, forcing the provider to take action against the sources of spam. To understand Level 3, it's helpful to know how the whole system works:
The project's various blacklists are rebuilt on an hourly basis, ensuring they are kept up to date. According to UCEPROTECT, millions of mail systems worldwide use their lists to filter incoming email.
The UCEPROTECT project is run by UCEPROTECT-Orga, an anonymous and exclusive group of skilled technicians. Their stated mission is to stop email abuse globally. The organization operates on the principle that it is more effective to force administrators and providers to secure their networks than to try and educate every end user.
Their system is largely automated. The core database is fed by a cluster of servers that operate spam traps. When a spam email hits one of these traps, the sending IP address is automatically added to the Level 1 blocklist, which can then escalate to Level 2 and Level 3 if the abusive behavior continues or is widespread within the network.
Getting removed from a Level 3 blacklist is complex because the listing is not tied to your specific IP but to your entire provider's network. The delisting process primarily relies on your provider taking action to clean up the abuse within their network.
According to UCEPROTECT, every IP address listed will expire automatically and free of charge 7 days after the last abusive email was detected. This counters a common myth that payment is required for removal. However, a Level 3 listing will only be removed once the number of associated Level 2 listings falls below a certain threshold. This requires the provider to resolve the spam issues coming from their network.
UCEPROTECT does offer an optional express delisting for a fee for those who do not want to wait, but this option is not always available. Express delisting is not possible under the following circumstances:
Before requesting any kind of removal, you must first ensure the underlying cause of the spam has been fixed. You can check your IP address on the UCEPROTECT website to see its current status.
The impact of being listed on UCEPROTECT DNSBL Level 3 is considered low by some, but it can be severe for those affected. A Level 3 listing means your entire provider's network is on a blacklist. This can cause significant email deliverability problems, as any mail server using this blacklist will reject emails from every customer of that provider.
Even if your own sending practices are perfect, your emails can be blocked simply because your ISP or hosting provider has a poor reputation according to UCEPROTECT. The impact ultimately depends on how many of your recipients' mail servers use this specific blacklist. Due to its aggressive nature, its adoption is controversial, but for senders affected, the disruption can be total for receivers that do use it.
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