Email definitely has its issues, but given that every other form of digital communication is getting worse and more locked down, I have no confidence that a replacement would be better. While increasingly difficult to get self-hosted email to be accepted by the big providers like Google and Microsoft, it is still great to at least have the option of hosting a universally accepted form of communication yourself.

There have been many fixes over the decades, but it's hard to change the fundamentals of something widely-used.

Do you have any suggestions on how to fix email?

From my perspective all attempts at fixing anything broke something for smaller senders. Today if you want to host a mail server you can set up everything correctly (SPF, DKIM, DMARC) and your email still lands in the spam folder because you have not enough reputation. There are whole IP address segments that a flat out prohibited from participating.

Email is designed to be a distributed system. That means new standards can not really be added without breaking most of the systems. We still don't have mandatory transport encryption. So I don't see how to fix anything but to improve spam filtering and accept that it will be imperfect.

There’s nothing to fall through, email fits it’s exact purpose. Email is supposed to have 0 sending/receiving friction. So one idea to fix it is to only accept email from addresses you’ve allowed. No one wants to constantly update their address book though, they just want the email (forgetting to remove the marketing email allowance after you receive the account verification link). So then there’s nothing to fix.

The abuse is by design.

Email is fixed by avoiding the usage. I only check my email for password resets and bank notifications. I never send email. Every other channel of communication with anyone outside of work is a text message.