Wednesday, December 27, 2006

RBL/Blocklists RIP? Hardly...

With the shutdown of the ORDB realtime block list (or blackhole list if you prefer), I have seen chatter in mailing lists, newsgroups, and newsletters claiming that the time of the RBL has past. One good friend of mine (that despises RBLs) claims they are ineffective and offer too much risk. There is too great a chance that a valid connection will be rejected to even consider using them.

My primary mail server gets a LOT of spam. I use the Spamhaus composite blocklist (SBL-XBL.SPAMHAUS.ORG) as my sole block list provider. Your honor, I submit the following in to evidence. (You can click on the image for a larger view.)

Out of the 163,000 connections made to this server over the last 5 days (yes, since Thursday before Christmas!), 111,000 of these were rejected because they were on the Spamhaus list. That is a whopping 68% of the connections that were rejected without having to accept the message or process it further. That is pretty darned good, IMHO.

The Intelligent Message Filter stats are above there. The SCL value is set to "Reject" anything above a 6 or above. Almost 88% of the mail inspected over this time was considered to have an SCL of 6 or above!

And the best part, I have not heard a single complaint in over a year about someone's message being rejected because they are on an RBL.


At 2:46 PM, Blogger Robert said...

I'm new to using IMF, but would love to know how you generated those stats for IMF and RBLs, so as to deminstrate the benefits of using IMF and RBL's to limit the footprint that spam puts on our systems.

At 1:44 AM, Blogger Iwhp said...

I would also be intressted about how you did this stats. Any comments?


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