"But my emails are just not delivered anymore. I might as well not have an email server."

I will never understand people who see it as an all or nothing proposition. You can perfectly self-host while using an outgoing SMTP provider. This would solve all the problems the OP is having while still preserving the main benefit of self-hosting, meaning: managing your own MX records, you own IMAP server, so that government authorities don't have a single organization they can target to get access to your emails. Heck, if you are paranoid you can even have multiple outgoing SMTP providers and round-robin between them.

Edit: the author does mention not wanting to pay for an outgoing SMTP provider, but there are many free option: for example Gmail lets you use their SMTP server as long as you authenticate with a (free) Google account. That's possible with Yahoo, or many other providers.