On Tue, 1 Oct 2002, Chris Wedgwood wrote:
On Wed, Oct 02, 2002 at 04:03:49PM +1200, Simon Lyall wrote:
For example one spammer sent us (over the weekend) 450,000 (approx) emails over 3 days. All of these were from (the same) bogus domain (optprofessional.com) .
So why did you accept them?
Because I thought he would go away after the first day. Also we very much avoid blocking email to customers.
Except for a very small list (less than 10 ) of sites we accept all email that comes in. Spam is only blocked for customers who subscribe to the anti-spam service and they are able to look at whats been blocked and retrieve it for up to 20 days afterways.
People do not accept their email being blocked and get VERY paranoid if they think email is not getting through. Dropping people's email to the floor is not an option in an ISP situation. At least IMHO, other people may have different ideas but I know at leasts one ISP used to lose customers due to the heavy spam filtering.
The ones that were blocked were *only* blocked because the volume or nature of their email was causing load issues for our servers.
w.r.t RBLs we use them as part of our anti-spam service, useful ones include bl.spamcop.net and kr.cluecentral.net and cn.cluecentral.net.
What software are you using for filtering? Some sort of Bayesian type thing?
-- Simon Lyall. | Newsmaster | Work: simon.lyall(a)ihug.co.nz Senior Network/System Admin | Postmaster | Home: simon(a)darkmere.gen.nz ihug, Auckland, NZ | Asst Doorman | Web: http://www.darkmere.gen.nz
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http://www.ietf.org/rfc/rfc2505.txt To whit: 2.9. Verify "MAIL From:" The MTA SHOULD be able to perform a simple "sanity check" of the "MAIL From:" domain and refuse to receive mail if that domain is nonexistent (i.e. does not resolve to having an MX or an A record). If the DNS error is temporary, TempFail, the MTA MUST return a 4xx Return Code (Temporary Error). If the DNS error is an Authoritative NXdomain (host/domain unknown) the MTA SHOULD still return a 4xx Return Code (since this may just be primary and secondary DNS not being in sync) but it MAY allow for an 5xx Return Code (as configured by the sysadmin). It doesn't actually say that you must drop mail from nonexistant domains, but it certainly implies that those sending mail with nonexistant domains shouldn't be suprised if their mail does get dropped. Cheers Si On Wed, Oct 02, 2002 at 05:26:23PM +1200, Simon Lyall said: - To unsubscribe from nznog, send email to majordomo(a)list.waikato.ac.nz where the body of your message reads: unsubscribe nznog