On 21/01/2010 11:59, Per Jessen wrote:
DNS checks would be overkill for a list that doesn't change that
often.
Overkill yes, but "affordable", especially with results being cached.
Personally I would favor DNS for data that _does_ change, even if
only very rarely.
It just doesn't make sense. Do you know how many requests they would
be flooded with if it was default SA option? It would query _all_
untrusted ip and by -clauses in Received path? How is that
"affordable"?
Well, it obviously depends on your setup, but even if you don't have
your own DNS, the results can be cached locally (nscd), so the overhead
is still not a lot (IMHO).
For individual mail servers doing DNS lookups, the overhead isn't a lot.
But the overhead for the person running the DNS system which serves the
data, is extremely large. Multiply the number of spamassassin
installations by the number of IPs they each look up per day. What is
that? Hundreds of millions of lookups? More? How many servers would be
needed to supply that sort of traffic with minimal downtime?
RCVD_ILLEGAL_IP is currently ranking 289th in my SpamAssassin rule
statistics having triggered on only 79 out of the last 66657 emails. Is
such an infrequently triggering rule worth having a dedicated DNS based
lookup system?
It's *much* more sensible to just push out the changes with sa-update.
--
Mike Cardwell : UK based IT Consultant, LAMP developer, Linux admin
Cardwell IT Ltd. : UK Company - http://cardwellit.com/ #06920226
Technical Blog : Tech Blog - https://secure.grepular.com/
Spamalyser : Spam Tool - http://spamalyser.com/
