The primary problem is that DMARC is fundamentally flawed, and was not enacted using a standards process that respected all of the stakeholders. As a result, it fundamentally becomes a matter of power politics.<p>If there are a bunch of people who need to participate in a particular mailing list --- say, IETF mailing list or the Linux Kernel development lists --- more than they need to stick with a particular mail provider, it becomes possible to say to them, "you want to participate in our community"? Change mail providers.<p>In the cases where a mailing list community badly needs the Yahoo users, Yahoo can dictate to the mailing list --- change your mailing list software and inflict pain all on your mailing list users, or you don't get access to our e-mail user community. (And rewriting the from field has all sorts of bad effects, including corrupting contact databases that auto populate based on names and addresses in the from field, making the mail summary index useless, breaking reply-to sender, etc. So there is real pain involved here.)<p>Part of the issue was that DMARC was originally intended for domains that only sent official announcements (e.g. for credit card companies or banks) and where employee e-mails came from a different domain. For that original use case, DMARC worked perfectly well. Apparently Yahoo then decided it had a terrible SPAM problem, and decided DMARC was a blunt instrument to use, and inflicted on consumer e-mails. Other companies didn't think ahead, and used the same domain for official e-mails as their employee e-mails, and decided that protecting their users was more important than inconveniencing their employees.<p>This is why it's ultimately all about power politics. If you want to participate in Linux Kernel development, you need an e-mail address that won't arbitrarily cause your e-mails to be dropped (for example, so Linus Torvalds doesn't get your pull requests). Despite this, growth in Linux Kernel Development continues to be growing, which means that when choosing between the inconvenience of changing or using an alternate e-mail provider, versus participating in Linux development, developers choose the former. But that only work because Linux has the economic power and clout to get away with it.<p>Heck, over ten years ago, refusing to buckle in to crap e-mail systems forced IBM to allow its Linux Technology Center folks install a standards-complaint IMAP server instead of using that abomination caused Lotus Notes which the rest of the company was forced to use. (And this was probably a better demonstration of the power of Linux, given how much IBM was stubbornly attached to Blotus Goats.) But make no mistake. This is Trump style, power politics. It doesn't hurt those with a lot of economic power, but if you're some tiny, podunk church mailing list, or some other group lacking in economic power, you're screwed.<p>DMARC: making email "great" again.