Spammers are better at SPF, DKIM, and DMARC than everyone else

For me, as someone with their own mail server, these technologies mostly serve to inform me that Russian IP addresses are still trying to send email in the name of my domain for some stupid reason.

It makes sense that people whose business is sending email know how to set up email correctly. I'm mostly surprised at how many legitimate sysadmins struggle with getting the basics correct. Surely those dozens of DMARC emails you get that your sendgrid email has been refused because of a bad SPF signature should set in motion some kind of plan to ask if maybe marketing is using them legitimately?

Automated signatures are of limited value but I rarely see rejections based on SPF and DKIM that are a mistake. Things are probably worse for big organizations but as a small email server, technical rejections are usually the right call. The only exception is mailing lists, but the dozens of people who still use those can usually figure out how to add an exception for them.

The problems I noticed were, it doesn't matter what the SPF and DKIM look like. If Google or Microsoft refuse to relay your email based on secret internal factors then you're out of business.

Best, and often practically only, way to avoid this problem is to buy your email services from Google Microsoft duopoly.