For what it is worth, if I turned off blocking at MTA level I would see a 33-40% increase in traffic. I don't want that. Every reject has a nice response saying where to email if you get blocked. I've got Delay_checks enabled. So I can override a listing.

I've had to do it 3 times I think. All 3 times the customer was grateful I had informed then they were on a black list. And I helped them to get off of it. So it was not a negative for our company, bit a positive.

Just the rants of a crazy man, --Chris

-----Original Message----- From: Rob McEwen [mailto:rob@pvsys.com] Sent: Saturday, August 14, 2004 4:52 PM To: 'SURBL Discussion list' Subject: [SURBL-Discuss] FP Pattern for sbl-xbl.spamhaus.org Importance: High

RE: FP Pattern for sbl-xbl.spamhaus.org

For a while now, my philosophy has been to use sbl-xbl.spamhaus.org to block at the connection level and not even allow these messages onto my server. Much of the remaining spam filtering is then done by SURBL-checking. However, more recently, I been testing samples of sbl-xbl.spamhaus.org blocked messages and I've noticed two things.

(1) more false positives than I would want to see (though still a very tiny, tiny percentage overall) get blocked by sbl-xbl.spamhaus.org

...and...

(2) those that ARE legitimate tend to be cases where a mistake was made and, by the next day (or later that same day), the offending IP is removed from sbl-xbl.spamhaus.org

However, I must admit, I'm drawing sweeping conclusions from very little sampling of data. Therefore, don't take my word for it... Rather, is this consistent with anyone else's experience with sbl-xbl.spamhaus.org? The reason I mention this is that, if my initial conclusions are true, there would then be a strong argument for "holding" sbl-xbl.spamhaus.org blocked mail and giving it a "second try" some hours later. Also, if this is true, does anyone have a "feel" for exactly how long "bad" data stays on sbl-xbl.spamhaus.org before it gets removed? (Recognizing, of course, that SpamHaus is probably the most reliable and respected free RBL in existence and they rarely make mistakes in the first place).

Any thoughts or suggestions? Has anyone examined their sbl-xbl.spamhaus.org blocked messages lately?

Rob McEwen

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