@jwz @dnalounge a mail server isn’t so hard to self-host (and I run my own).

But Google and Microsoft have made damn sure that running your own mail server while also relaying emails reliably to accounts on their servers is a nightmare - and called them “antispam measures”.

The entry barriers are so high that only persistent geeks keep pushing (and I still have to relay most of my emails through an external SMTP just to make sure that they get delivered to Microsoft). Everyone else was happy to stick on Microsoft’s or Google’s servers. It should just be a matter of securing access to the server, adding the right SPF, DMARC and DKIM records to the DNS, show for a bit that you’re a good citizen on the Internet and you don’t end up on Spamhaus, and you should be able to send emails. But those two actors (especially Microsoft) have created such a maze of invisible checks that very few bother to navigate.

Btw your stats miss something even more alarming: that it’s likely that a big chunk of those in that 5-6% “other” bucket still use Google or Microsoft - just with a custom mail domain still hosted on their boxes.