On Wed, 15 Nov 2006, Martin Kealey wrote:
We've recently tightened up the reverse & forward DNS tests applied by our inbound SMTP servers (zuul.ihug.co.nz); sending hosts with mismatched DNS entries are now likely to have all messages rejected.
What percentage of spam does this rule block and the reasoning as to why it would block more spam but have a low false positive rate? I'd suspect that it won't be a big win by either criteria, on the other hand it probably wins with the "simple option to enable" criteria. Since you are using Ironports and already throttling or blocking connections from many bad IPs the win should be further reduced. http://news.com.com/2100-1023-982118.html -- Simon J. Lyall | Very Busy | Web: http://www.darkmere.gen.nz/ "To stay awake all night adds a day to your life" - Stilgar | eMT.