When I first read about HashCash in 2004, I thought to myself: "What a great idea! I'm sure someone will add it to my e-mail client soon," and I went happily on my way. Two years later, the trickle of spam has become a flood, my Bayesian filter is overwhelmed, and... HashCash seems to have vanished into obscurity. There was a flurry of articles and interest in 2004, a few in 2005, and then... nothing. I was surprised to find that Thunderbird still has no HashCash support. It's a popular mail-reader, open source, with a plugin architecture. A quick check on Bugzilla shows that the HashCash feature request is in the top 20 (out of thousands!) by number of votes, but nobody seems to be working on it! What happened? Spam is an ever-more-painful thorn in the side of every computer user, so I would expect to see whole teams of open-source programmers inventing a bazillion different ways of fighting it. Instead, I see filters, and filters, and yet more filters. I would have thought that the decision to implement HashCash was a no-brainer. It's very simple to implement, it has the overwhelming advantage (compared to DomainKeys etc.) that it doesn't require major infrastructure changes, and it can be optionally enabled on a per-user basis. This is a perfect opportunity for the open-source community to lead the entire industry. As I see it, this isn't a technical problem. You folks at hashcash.org have written the basic software. It's been part of SpamAssassin for years. All we need is client (MUA) support, and it's not your job to integrate it into every e-mail client. This seems to be a political/PR problem. I am totally mystified as to why there is so little interest from the authors of e-mail clients. I assume that you've had many discussions with the mozilla developers and others -- what was the response? Why the lack of enthusiasm? -DeLesley