Reverse DNS and SMTP

Jared Mauch wrote:

        What I do is format my smtp headers such that a very simple
regex can find mail with no reverse dns and dump it in a spam folder.
I find this catches a lot of the messages.

If your server is using a heuristic that has the potential of offending
your customers, you can make the blocking optional.

More specifically, respond to the "spam detected" condition by writing a
header that customers can check for. Once that header's in place, a
customer can configure his mail client to accept, delete, or spam-folder
the message. If a client wants these kinds of messages to be deleted on
the server, that may not be too hard to do either, once the header is

-- David