Owning the domain makes for great email address portability. If I hadn't read so many of your comments here over the years, I probably wouldn't suggest this, but I think a good strategy is to buy 2 domains, one for trusted entities (i.e.people you know or your bank/ credit union) and one for non-trusted entities (i.e. Amazon or commercial entities in general). Use your domain registrar's email hosting for trusted entities (add PGP for extra goodness), and use a commercial provider (e.g Google, Fastmail,etc.) for the non-trusted entities domain.

Strange, my spam filter is fine. Premium is just no ads + some extra space. I pay premium because I want microsoft to keep providing this excellent service without compromising my personal data