Apologies, I was thinking of the spamhaus list, which I'm also not sure now is crowdsourced in the sense most people would use.
But most email providers build spamfilters using 'crowdsourced' techniques between their users (if enough users mark a sender spam it might be marked spam for all users).
And while that may be controversial, it's also highly effective.
But most email providers build spamfilters using 'crowdsourced' techniques between their users (if enough users mark a sender spam it might be marked spam for all users).
And while that may be controversial, it's also highly effective.