Ask Bjørn Hansen wrote:
On Feb 17, 2010, at 3:41, Jost Krieger wrote:
1. How many SMTP sessions can be expected on commodity hardware under
Linux (RedHat), with prefork?
If you don't do any heavy processing (spamassassin or virus scanning basically)
then ~20/second (or whatever a million day works out to when your server is
busiest) shouldn't be a problem.
If you do spamassassin and such, that will be the resource intensive part.
qpsmtpd might help over other MTAs though in filtering more of the mail in
cheaper ways first.
2. How fast is this (I've read Chris Lewis saying 300 sessions/sec)?
That doesn't sound unreasonable, but as soon as you add the spam filtering it
goes down -- imagine even just 5 DNS lookups for blacklists and such and now
you're also doing 1500 DNS lookups a second.
We achieve 100-150/second per server (relatively modest/oldish hardware)
with full DNSBL, ASN lookups (via DNS), EL, various pattern matching, SA
and ClamAV _and_ never sending the reject until after the DATA section
is sent (except no-such-user) so we can do 100% spam quarantine of
everything we've rejected.
We can do this because we "turn off" subsequent plugins/filters once an
earlier one has said "I'm going to reject this email".
It also depends on your spam/ham mix.
If you were rejecting at the time you say "nope, don't want it", you can
do more.
