On Wed, Apr 05, 2006 at 06:37:48PM -0400, Sam Varshavchik wrote: > Sander Holthaus writes: > > > > what is your opinion on greylisting? Any specific reason why it is > > not included in Courier? > > > Because I have a job, and not enough free time to do it right. Busy > mail servers may receive hundreds of connection attempts per second. > Assuming a baseline of 100 connections a second, and a greylisting > expiration interval of two hours -- you can't really have an effective > greylisting system with a shorter expiration, because it's quite > reasonable for legitimate senders to wait at least an hour to try > again -- simple math will show you that your greylisting database is > going to grow to the 700,000 record range. > > Before I could even think of writing a single line of code, I have > to figure out how to scale to a database that may potentially hold > several million records, and do it in a way that allows for parallel > queries -- and updates -- with negligible overhead.
You might get something out of reading the code for OpenBSD's spamd. The spamd author's setup (http://www.openbsd.org/papers/bsdcan05-spamd/mgp00019.html) - A Dell 1U (pe 1650) runs 95% idle 5% system doing greylisting - 850 000 connections over a 36 hr period (avg of 6/sec) On our setup, we have nearly 2 million blacklisted IP's (cbl.abuseat.org), 100,000 whitelisted, and 15,000 greylisted. (A greylist entry stays active for four hours.) This IBM X330 also runs the ESMTP daemon, spam assassin and clamav (with clamcour). I'm accepting mail for over 8,000 users. The load avg is somewhere between 0.5 - 1. pf's table lookups are extremely fast, that's partly why spamd works so well--the black/white ip lists are loaded as pf tables. So these setups doen't meet your requirements but it's probably the closest thing out there now in production. I think it just uses a Berkely db. For you reading pleasure ... http://www.openbsd.org/cgi-bin/cvsweb/src/libexec/spamd/ and here: http://www.openbsd.org/cgi-bin/cvsweb/src/usr.sbin/spamdb/ m ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ courier-users mailing list [email protected] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
