[Mimedefang] Discarding fake MXs

[Andrea Venturoli]

Hello.

Lately I'm seeing a lot of very nice people who set their second level domain's MX to something like 192.168.x.y.
Obviously no mail will ever reach them, but i'd rather discard it immediately, rathar than having several retries and
several error messages in the logs.
I don't think sendmail can do this, but hey, I'm using mimedefang :)
Really, I'm no perl guru, does anyone have any snippet?
Should this go into filter_recipient?

 bye & Thanks
        av.