> I've run my own for about 4 years now with mail-in-a-box. It's on digital ocean, and it delivers fine to everyone. Like others have said, you just have to watch the lists to see if you end up in a block of IPs that gets blacklisted

This is not true. I've also run my own server for several yes (on AWS), I've never seen the IP on any blacklists, and yet my deliverability to Outlook and Gmail is extremely bad (I've since moved on to using Postmark for sending emails).