I should be able to refuse emails and not get spammed with life ending phishing and malicious links around every corner.
Email providers shouldn’t be able to whoopsie and delete emails on my behalf, or gatekeep information that’s needed in court.
Self hosting doesn’t fix the core problems with email even if you don’t screw it up, which you will.
Phishing and malicious links exists on every kind of messaging - email, forums, whatsapp, telegram, SMS... you name it, it has spam/phishing. You'd think that at least "real name" or "pay a bit per message" might discourage this, but example of SMS (text) shows otherwise.
With any system the server operator will be able to delete messages, and/or gatekeep information - unless you have some sort of "big brother" setup where every message goes through government-operated monitoring server, and I cannot believe anyone intentionally choosing such a system.
(steps on soapbox) And as long as we are talking about SPAM, why in God's name if I block a text message and then the phone number from ringing is there an additional block required to prevent voicemail? Oh, I see, it is so Verizon and others can charge me to block voicemails. Even on Google FI, if I block a number on Messages it doesn't carry over to calls which doesn't carry over to voicemail. Enshitification. (steps down)
Basically you had to play a (very small) amount to charity to cold-email someone (and with an escape hatch if you state you know the person)
That system would basically gate all spam without changing much