[Junk Email Filter]

Our list server is hostkarma.junkemailfilter.com - this server returns several different results depending on what kind of listing it is. If the server returns 127.0.0.1 then it is whitelisted. You can accept the email without any further checking.

If the result is 127.0.0.3 then the host is yellow listed. Yellow listing means that host generates some spam and some nonspam. (examples, yahoo.com, hotmail.com) What that means is that this host should never be blacklisted and that other IP based blacklists should be bypassed to prevent false positives. If the result is 127.0.0.2 it is blacklisted - if the IP is listed here you can bounce it without further checking.

And if the result is 127.0.0.4 it is brownlisted which means it is on its way to being blacklisted but hasn't quite got there yey. But it might be worth a few points using SpamAssassin.

• 127.0.0.1 - whilelist - trusted nonspam
• 127.0.0.2 - blacklist - block spam
• 127.0.0.3 - yellowlist - mix of spam and nonspam
• 127.0.0.4 - brownlist - all spam - but not yet enough to blacklist