Spam probably isn't as bad as you think it is. It's not the dark old days where 99% of emails are spam.

You should self-host, so you can do the experiment for yourself. You might be surprised. You can always stop self-hosting if you don't like it.

I wish that was true for all cases. My uni email is 99.9% spam and everything comes from official accounts sending irrelevant stuff to everyone and their grandma

Recent estimates show it's down closer to 50% of all emails now. Which is obviously still outrageous.