It would also help if you did step 0: buy your own email domain

Personally, I love sending emails nobody will receive, it removes inhibitions and lets me speak my mind without regrets!

This isn’t as hard as you might think. I pay for https://mailwip.com because the founder helped me figure out mine. It was ultimately relatively strait-forward. I stay because I appreciate his work, my email is flawless, and I like the logs they provide.

this is really good thanks!

I've been self hosting email for a few years at this point and haven't had any delivery issues. Just make sure you set up all your DNS correctly and avoid polluted IP ranges like DO or AWS

This does not happen if you use a well known MX host