100% spot on. I did this for many years, and the sysadmin stuff was actually a fun little hobby. There were many seasons in terms of deliverability. I only ran personal email, never a list or anything like that, my ip wasn’t on any black list, but from time to time emails wouldn’t be delivered, or they would start going to peoples spam folders. I’d get fixed what I could using google/outlook/whatever’s tools or reach out to the mail admin address. Many times deliverability would be fixed, but months later the cycle would repeat. Or worse, I’d get silently and suddenly banished to spam. There’s nothing more you can do about that (yes I had all the things to prevent it).
Ended up moving my mx records to fastmail and using them for email. It’s not much, if any, more cost than running a vps for email (well, if you only consider one user), but I’ve had drastically improved deliverability.
Long story short, email is terribly broken, but it’s a good idea to have your own domain so that you own your address.
Fine! .csv.gz ftw!