Ask HN: How do people self host email and maintain deliverability?

I wanted to self host my email and decided to rent a VPS. I made sure the ipv4 address was on no blacklist. My domain uses a good TLD with a long domain history. I set up SPF, DKIM, DMARC, reverse IP DNS, etc.

I sent 3 emails to my personal outlook/hotmail accounts, all of which went to spam. 1 day later, my IP was banned. Outlook support said they cannot discuss the reason for the ban and will not unban it so I'm out of luck.

I know I can just pay a provider $5/month and get email, but there is something about having full control over your own email. Is there anything much I can do?