I am going to point out now that I've been running my own mailserver for 15+ years
And I can't send mail to people with Apple or Google accounts. Why? Well, I'm not a known corporate entity. They whitelist email to known large businesses, an unrecognized IP gets blocked directly.
So y'know, yeah. Globally recognized protocol, got all the SPF/DKIM/DMARC/etc, but when it comes down to it, once big business gets a majority of an open protocol? They will devour it
It's been a big #problem for years, though it's getting #worse. The #Gmail / Outlook-Hotmail-Office365 / Yahoo triumvirate have backroom deals so they don't have #deliverability issues to each other. But the small guys have trouble delivering to them - particularly Gmail.
I've run my own mail server for going on 25 years now. For the last 15 years it's had the same IP. Strict #SPF & #DMARC, correct #DKIM & #DNS. Zero #spam. And I still have deliverability problems.
[...]
Part of the problem is Gmail's huge #influence. Like Lily Tomlin said, "We don't #care. We're the phone company, we don't have to.". So they don't give a damn if smaller domains have trouble delivering to Gmail #users. It's not like Gmail users have any way to actually inform Gmail that they're not getting their #mail.
And I'm sure it's just a #coincidence that the #problem just increases Gmail's business. People give up hosting, and #outsource their email to Gmail.