On Tue, 11 Aug 2009, Exim wrote: > From: Exim <[email protected]> > To: [email protected] > Date: Tue, 11 Aug 2009 18:30:39 -0500 > Subject: [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).
Once such client that implements this is the Tagged Message Delivery Agent (TMDA): http://tmda.net/ The documentation indicates that it works with exim. I've never tried it so can't say for sure. As others have pointed out, these challenge-response schemes are considered a *BAD* idea by some. Google searches using keywords: "challenge response email problem" will throw up articles reflecting this view: http://www.politechbot.com/p-04746.html http://www.tardigrade.net/challengeresponse.html There are probably other such articles lurking on the Internet. I've found such systems to be bloody annoying when I've met them. Especially when I've been privately replying to a request for help on a mailing list. So I've I've been quite content to not reply and be classified as non-human. Perhaps I'm just intolerant... -- Dennis Davis, BUCS, University of Bath, Bath, BA2 7AY, UK [email protected] Phone: +44 1225 386101 -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
