[Greylist-users] What timeouts should be used with greylisting

Evan Harris eharris at puremagic.com
Wed Jun 25 19:45:23 PDT 2003

While coding the initial implementation, I toyed with the idea of trying to
tarpit the connections, but for exactly the reasons David described, I
decided it wasn't worth it.


On Wed, 25 Jun 2003, David F. Skoll wrote:

> On Wed, 25 Jun 2003, DJ Delorie wrote:
> > What I do is add a 60 second delay before sending them the error code.
> That's fine on a small mail server.  It's horrendous on a busy mail
> server.  You'd see sendmail (or exim or qmail or whatever) processes
> backing up like crazy, chewing up your virtual memory.
> Believe me, I know that adding delays to responses on a busy server
> hurts. :-(
> > It's not the bandwidth that's important, it's the number of emails per
> > hour they send that is.
> Multi-threaded spam engines on commodity hardware can easily run
> thousands of parallel SMTP sessions simultaneously and probably
> saturate a 100Mb/s Ethernet.  Adding delays on your end will have an
> infinitessimal effect on hard-core spamware.
> --
> David.
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