Marjorie Roome via Dng <dng@???> wrote:

> I configure strict postfix rules that incoming mail should have a
> reverse DNS.

Ah, we’re talking two different checks. I too reject connections if there’s no reverse DNS, but ideally that reverse DNS should forward resolve to a list (one or more IPs) containing the IP of the connecting device. It’s this latter bit that people seem too incapable of getting right.

But while rejecting “no reverse DNS” does block a lot, there is a lot of spam that comes from addresses that have generic reverse DNS entries - many ISPs have reverse DNS setup for their customer IP ranges along the lines of a-b-c-d.dynamic.ispname.net.

I find grey-listing to be by far the most effective spam blocker.


Simon