• All Janet services are governed by the Janet policies.

Janet has its own copies of the following leading allow and deny lists:

• Spamhaus Zen lists
• URIBLs
• DNSWL.org

DNS deny lists 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.

Allow lists contain all currently known good email servers, and are the opposite of deny lists, mail from the allow listed e-mail addresses, domains, and/or IP address should generally be allowed. Using Allow lists and deny lists assists in blocking unwanted messages while allowing wanted messages to get through. E-mail allow lists 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 deny lists, 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 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:

• What to do if your mail is being blocked