Re:Crowdsec: A Fail2Ban alternative written in Go
by monadic2 on Monday October 19, 2020 @01:33PM
(#24828684)
Speaking from personal experience working with these reputation warehouses and with handling a good deal of incoming and outgoing email volume, they aren't any more effective than other IP-based spam heuristics and if everyone configured their DKIM correctly these warehouses would be largely obsolete. I don't see a problem with crowdsourcing heuristic data per se, but email is a much narrower field than internet traffic at large and I can see a lot of the ways that poorly configured fail2ban type software could accidentally ban a lot of valid traffic.
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.