And what do you actually use? I know the answer is probably self-hosting but maybe there are other solutions for a decent privacy.
I think that misses the point. Emails are kind of antithetical to transient and private communications. People are much better off using a generally respectful service that doesn’t scan their mail for normal use and turn to better tools like Signal (which require both receivers to use an agreed-upon/enforced and privacy-focused infrastructure) or any other messenger with disappearing chats that limits metadata retention.