[exim] Are you human?

I just had a client ask for something I haven't done. He wants emails from
unknown users to be sent back with a "are you human" request they must
respond to correctly. If they do, then they will be automatically added to
a list of valid senders.



I have heard of this idea some time ago, but for the life of me can't
remember what it was or how to implement it



(and no I don't want to do this, but sometimes you have to do what the
client demands, rather than what is really best for them).



Terry Shows

Nashville, TN