[Mimedefang] thoughts on "nolisting"?

[WBrown at e1b.org]

Gary Funk wrote on 09/10/2008 12:31:00 AM:

> We've grown a bit frustrated by the amount of spam that flows
> through our backup MX server.  Was recently reading about the
> "nolisting" technique,  http://en.wikipedia.org/wiki/Nolisting
> where bogus MX servers (primary and highest numbered backup)
> are set up, in the hopes that dimwitted spam clients will
> bounce off those bogus servers.
>
> Anyone tried this?  Opinions on pros/cons?
>
> BTW, it seems to me that more ideal backup MX behavior
> might be for the backup to poll the primary, every minute/so,
> and only open port 25 when it determines that the primary
> isn't available ....

I played with it briefly and did not notice much of a decrease in spam
coming to the actual servers.  However, I do not have any backup MX servers
that are not running filtering.  My understanding is it only offers some
value when you have unfiltered backup MX servers.  Is your backup MX not
filtered?  Can that be changed?

It is certainly a low cost technique, so there's little reason not to try
it.  Let us know how it works for you.