DNSBL

DNSBL

DNS Block List.

A DNSBL is a list of DNS entries from which incoming emails should be blocked. It is also known as a DNS Black-hole List, or IP block list.

DNSBLs typically list open relays and servers which can be used for RNDR attacks. These are typically used as a means to reduce spam by blocking emails from known (or likely) spammers. However, it should be appreciated that DNSBL works on listing IP addresses and does not provide any intelligent filtering based on the content of an email.

DNSBL can be created and customised within a company, but there are also third party DNSBL services available on the internet.

DNSBL are sometimes also referred to as RBL or simply BL.

For more information see:

• www.spamhaus.org - Possibly the most well known DNSBL.
• www.moensted.dk/spam - Extensive list of DNSBL and related services on the internet.
• http://shopping.declude.com/Articles.asp?ID=97 - Extensive list of DNSBL service providers.
• http://dmoz.org/Computers/Internet/Abuse/Spam/Blacklists/ - List of DNSBL and related services from DMOZ.
• www.robtex.com - Performs an online check of an IP address against multiple black lists.
• www.anta.net/irt/blacklisted.shtml - Generic help for administrators whose networks or servers have been blacklisted

  Contributed by Thor Kottelin