Comment Prior Art (Score 1) 336
Mailblocks acquired two patents for challenge-response, which were granted in 2000 and 2001, respectively.
I've been a Spamcop member for at least three years now (oldest spamcop mail I have is Nov 1999). Spamcop has (did have?) a challenge response system back in the early days. Not sure if it's still available (I've set my filtering to always block a long time ago). But I'm sure that Spamcop's challenge response system predates Mailblock's.
I've been a Spamcop member for at least three years now (oldest spamcop mail I have is Nov 1999). Spamcop has (did have?) a challenge response system back in the early days. Not sure if it's still available (I've set my filtering to always block a long time ago). But I'm sure that Spamcop's challenge response system predates Mailblock's.
