On Wed, 10 Jun 2015 13:56:49 +0000 David Jones <djo...@ena.com> wrote:
[One should run a caching DNS server on a mail server.] > We are giving you solid advice based on real experiences where we > ran into problems and worked around them. Just try to enable RBLs > and see how it works for you. I'm not disputing that running a caching DNS server is a good idea, but you may be quite surprised at the low cache hit rate for IP-based DNSBLs. Spamhaus, for example, has a TTL of 1 minute on its A records. (Check out "host -v 2.0.0.127.sbl.spamhaus.org" if you don't believe me.) Quite a number of years ago, I ran an analysis of the mail logs on a very busy server and found an abysmally low cache hit rate (about 30%) and that was in the day when Spamhaus had a 15-minute TTL. Anyway, run through the exercise yourself; it's eye-opening. My original post was here (back when I used to be David, so don't let the signature confuse you...) http://spamassassin.1065346.n5.nabble.com/Fwd-Asrg-draft-levine-iprangepub-01-tp28778p28802.html Regards, Dianne.
