SpamCop Blocking List [long]

For all you long-time SpamCop users, the SCBL is not anything new. 
However, for a lot of you newer folks, and those who simply use 
SpamCop for reporting, you may not be aware of it.

For years, there have been a variety of DNS-based blocking lists 
(DNSbl's)[1] on the internet. The MAPS Realtime Blackhole List 
("RBL")[2] was the first, and one of the largest, most influential 
entities on the internet. If they added an IP address to their list, 
mailservers which checked incoming mail against the RBL would reject 
mail from that IP address. Their listing practices were conservative, 
and won great acclaim from internet users and administrators. It is 
estimated that at their peak, the RBL was used by over 40% of the 
mail servers on the planet. However, their popularity would be their 
undoing -- their expenses grew so large that they had to start 
charging for access to the RBL to cover their costs. Their popularity 
declined rapidly, and a bunch of alternate DNSbl's sprung up.

Several of these DNSbl's test against open relays, or open 
proxies[2]. They are quite effective for detecting technical flaws, 
and they're generally considered "safe"[4] to use to block mail from 
-- you can say "Your server has a technical flaw which leaves it open 
to abuse. It is our policy to not permit this, so until you fix your 
server's flaw, we will not accept your mail."

Other DNSbl's were based on their author's opinions -- SPEWS.org and 
SpamHaus.org are examples of this. SpamHaus is much more conservative 
of SPEWS, and has narrowly-defined listing policies, so it's used in 
wide circulation. SPEWS is more aggressive, and operates from a 
lawsuit-proof[5] position of complete anonymity. Of course, using 
these lists means that one needs to trust the opinions of the list