Earlier quoted context omitted.
Agreed! I've been running my own mail server for 20+ years, and I would not recommend that anybody do this on a lark. Deliverability to GMail is a huge problem for me and has been for years. I even asked friends at Google to find out what the story was. All I got back is that the mail group was so careful/paranoid it wouldn't talk to them either. I would long ago have switched over to a vendor, but I use qmail-style…
+1 about the opaqueness of gmails spam filters. I once had an email from a google recruiter (@google address) go to spam in gmail so at least it's somewhat egalitarian (that was 5+ years ago).
More, google knew this was a thing because they warned me.