It’s not only self-hosted email that is affected. My main email address is the one attached to my domain, which I’ve owned for over 20 years, and is managed by my webhosting company, a perfectly respectable, legitimate business that at one point handled about a third of all internet traffic in my country. This company is, nevertheless, not considered trustworthy enough for emails through their servers to reliably be delivered to their destination. I increasingly have to use an email address from a major multinational corporation because the email address from a merely large national corporation only has a 50/50 chance of reaching the recipient.