Even when gr[ae]ylisting was introduced (see <http://projects.puremagic.com/greylisting/whitepaper.html> http://projects.puremagic.com/greylisting/whitepaper.ht

Even when gr[ae]ylisting was introduced (see <http://projects.puremagic.com/greylisting/whitepaper.html> http://projects.puremagic.com/greylisting/whitepaper.html>), it was quickly recognized that there are some important sites out there that don't follow the RFCs, and therefore they break gr[ae]yisting. The page at <https://www.greylisting.org/whitelisting.php> https://www.greylisting.org/whitelisting.php> links to a source at <http://projects.puremagic.com/web-svn/wsvn/greylisting/trunk/schema/whitelist_ip.txt> http://projects.puremagic.com/web-svn/wsvn/greylisting/trunk... that doesn't even exist anymore. For postfix, we now have the project at <https://github.com/stevejenkins/postwhite> https://github.com/stevejenkins/postwhite> to help automate the maintenance of whitelists of sites that break gr[ae]ylising. IMO, we passed the point years ago when gr[ae]ylisting was still a useful technique. For anything within the last decade or so, I would say it probably does more harm than good.