Does anyone use Hashcash? I haven't run my own personal mail server in 5+ years, but I used to feel like Hashcash really helped keep my messages out of spam folders. It seems like SpamAssassin is really the only filter that implements it, and I don't know how prevalent that is today. But I used to spend 10-60 seconds computing a hashcash on every outgoing message that left my server, and has basically no problem with getting caught as spam. But I also had a domain and IP address with like 20 years reputation behind it...