The Tornevall Networks DNS-based Blackhole List (DNSBL) is a blacklist (or blocklist) that identifies and lists IP addresses involved in various abusive activities, including proxies, phishing, and both email and web-based spam.
The Tornevall Networks DNS-based Blackhole List (DNSBL) is a type of blacklist that identifies IP addresses associated with spam and other malicious activities. It is built on the Domain Name System (DNS) and allows mail servers to query it in real-time to check if an incoming connection is from a listed IP. Its policy focuses heavily on identifying open and anonymous proxies, including nodes on the Tor network, which can be used to obscure the origin of abusive traffic. This blocklist is also used to identify sources of phishing, fraud, and email spam.
Technically, the blacklist uses bitmasking to provide specific reasons for a listing. When a mail server queries the DNSBL about an IP address, the response indicates the type of activity detected. The main zones are dnsbl.tornevall.org, opm.tornevall.org, and bl.fraudbl.org. The return codes (bitmasks) include:
The DNSBL is operated by Tornevall Networks, a private, non-profit service provider and open-source developer. The organization was founded on principles of independence and self-sufficiency, initially creating applications for private use that were later released as open-source projects for public benefit. The DNSBL is one of its longest-running projects, originally designed to combat web-based spam but later expanded to include email spam. The project is split into multiple parts, including a standard blacklist for proxies and mail spam, and a separate blacklist, FraudBL, which has a higher spam score.
To get delisted from this blacklist, you must first resolve the underlying issue that caused the listing. This could involve securing a compromised machine, stopping a spam campaign, or closing an open proxy. Once you have fixed the problem, you can request removal using the official delisting form.
Keep the following points in mind during the removal process:
The impact of being listed on the Tornevall Networks blacklist is generally considered low. This blocklist (or blacklist) is not as widely adopted by major mailbox providers compared to some other more influential lists. However, its primary focus is on stopping web-based spam and abuse from proxies, which means it is used by a variety of system administrators to protect web applications, forums, and other online services. While it also lists email spam sources, a listing may not cause widespread email delivery failures but can result in your emails being blocked by organizations that do use this specific DNSBL. Therefore, it is still important to seek removal to ensure maximum reach and protect your sender reputation.
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