<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">On 2 Apr 2022, at 6:23 PM, Jeroen Massar via NANOG <<a href="mailto:nanog@nanog.org" class="">nanog@nanog.org</a>> wrote:<div><blockquote type="cite" class=""><div class=""><div class="">There are a lot of bits and bobs that one has to get right for mail to flow, amongst which:<br class=""><br class=""> - IP -> PTR lookup -> that hostname lookup, and match to IP again<br class=""> (<a href="https://en.wikipedia.org/wiki/Forward-confirmed_reverse_DNS" class="">https://en.wikipedia.org/wiki/Forward-confirmed_reverse_DNS</a>)<br class=""> - SPF<br class=""> - DKIM<br class=""> - DMARC<br class=""> - ARC (for mailinglists)<br class=""> - SRS (When forwarding, rewrite the From and resign DKIM, and then ARC-sign that)<br class=""> - Decent TLS<br class=""> - MTA-STS<br class=""></div></div></blockquote></div><br class=""><div class="">Jeroen - </div><div class=""><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class="">It is indeed amazing how many protocols we can spin up to address the same underlying problem, time and time again... </div><div class=""><br class=""></div><div class="">If anyone can anonymously join the mail-sending club and send some email [until bad reputation precludes such], and achieving bad reputation results has no real-world implications, and a new network persona (e.g. domain name) is always available, then the problem could be considered intractable by initial conditions – and no amount of anti-spam protocols (no matter how brilliantly designed and engineered) should be expected to durably address the problem. </div><div class=""><br class=""></div><div class="">(It might, however, be interesting to do a regression analysis on the spam mitigation protocol introduction dates – it’d be interesting to know if the expected number protocols that will need proper setup in 10, 20, 40 years…!) </div></blockquote><div class=""><br class=""></div><div class=""><chuckle> </div><div class="">/John</div><div class=""><br class=""></div><div class="">Disclaimer(s): my views alone. This email composed of 100% recycled electrons. </div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div></body></html>