Hi Rob, At 11:34 27-07-2004, Rob McEwen wrote:
I never mentioned this before, but these extra lookups can be like firecrackers going off. I do three types of DNS lookups:
[snip]
(3) content RBL lookup for IP addresses (not domains) using sbl-xbl.spamhaus.org
(BTW - Does anyone have a "feel" for sbl-xbl.spamhaus.org and false positives. I wonder sometimes if that particular RBL list is too strict?)
The RBL is not too strict. It does however cause false positives. This only affects customers relaying off your mail server.
Also, my mail server software is NOT know for robustness and several articles on their user's group site mention that it falters if the DNS server is slow or has any problems.
If the DNS server is slow, it will cause problems. If you are going to use DNS based blacklists, you should have a reliable DNS server.
Regards, -sm