DNS Blocklists and Whitelists

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Janet has its own copies of the following leading DNS blocklists and whitelists:

DNS blocklists are a well-established technique. They identify sources of e-mail abuse as lists of IP address blocks, enabling Janet organisations to quickly and easily reject a high proportion of unwanted e-mail.

Whitelists contain all currently known good email servers, and are the opposite of blocklists, mail from the white listed e-mail addresses, domains, and/or IP address should generally be allowed.   Using whitelists and blocklists assists in blocking unwanted messages while allowing wanted messages to get through.  E-mail whitelists are used to reduce the incidence of false positives and to speed up the filtering process, as they are often based on the assumption that most legitimate mail will be from a relatively small and fixed set of senders.

Unlike most blocklists, SURBLs and URIBLs are not lists of message senders but URLs (Web addresses, some but not all representing undesirable sites) which have been seen in e mail messages identified as spam or phishing, or are otherwise dangerous. Links seen in such messages tend to be more stable than the rapidly changing botnet IP addresses used to send the vast majority of them. The Spamhaus sender lists can be used in a first stage filter and the SURBL and URIBL lists can help in a second stage filter to find many of the otherwise difficult, remaining unwanted messages.

If you think that a Janet DNSBL is affecting the delivery of your e-mail messages, please read this page: