As the title says, what are your opinions on self hosting a mail server nowadays?

Just as a challenge to myself, I tried to set up a mail server in my personal homelab and I successfully made it not being marked as spam or rejected. It's still an early-stage experiment for me, but it has run for the past 6 months without a problem.

I also wrote a blog post, describing how I got there, I'd like you all to take a review and give me some comments or opinions on how to make the content more useful and easy to read (don't be cruel, please, it's my first post!).