[Mimedefang] temp failing - got code?

[Gary Funck]

Would like to implement temp failing/grey listing along the following lines:

- If haven't seen a given incoming IP address in a while, then temp fail,
for
  say about 1 hour.  If the sender doesn't just go away by then, then socre
  the mail per usual and let it through.

To implement this, we'd need a persistent data base (perhaps a local DNS
sever
like Tiny DNS?), I'd suppose.

My thinking is that if we hold off on accepting incoming mail from new IP
addresses,
it gives time for the various distributed spam registry databases to
register
the spam, its URL's and so on, thus making the 'network checks' more
effective.
That's assuming of course that the sending IP even bothers to retry.

Have you done something like this, and have code you could offer as a
starting
point?

thanks.