Penguin
Annotated edit history of RBL version 2, including all changes. View license author blame.
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1 PerryLorier 1 [Acronym] for __R__ealtime __B__lack __L__ist
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2 AristotlePagaltzis 3 A constantly updated list of hosts sending [Email] you may wish to reject. Originally created to list open relays abused to send [Spam], there are now various [RBL]s which also blacklist hosts for reasons such as being an open [Proxy], sending [Spam] directly, or having political views that oppose your own.
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2 AristotlePagaltzis 5 [RBL]s are usually queried via [DNS], by looking up <tt>''ip''.rbl.example.com</tt>. Lookups for blacklisted hosts return an A record (usually for 127.0.0.2) and/or a TXT record (explaining why the host is blacklisted).
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2 AristotlePagaltzis 7 [MailServer]s can be configured to check [RBL]s to determine whether they should accept an incoming [SMTP] connection. Most people subscribe to multiple [RBL]s.