Many years ago (20 ?) I used a tool called "Active Spam Killer" (ASK)
which would send a quick email challenge to a new sender forcing them to
respond and confirm ... and if they did not respond properly their email
would never hit your inbox.
It's a simple whitelist-only approach that blocked all senders except
those that passed the (very simple) email test. No web page was involved.
ASK is officially deprecated now:
http://a-s-k.sourceforge.net/
... but for a variety of reasons I would like to implement this same kind
of system ...
Does anything like this exist, off the shelf, for opensmtpd ? has anyone
already solved this problem in a modern way ?
I know there are many interesting and effective ways to deal with spam,
but for this particular project THIS is the way I want to deal with it.
Thanks.
