I've come to the conclusion that email will never be secure. I've settled for keeping my email data out of the hands of banks and advertisers by using Fastmail, and wildcard aliases. If I were doing any kind of journalism, politics or security sensitive work (I'm not), I would rely on solutions that are built on a foundation of end to end encryption like Signal. I try to use Signal as much as possible not because I'm discussing sensitive things, but just because I want more people to use it so that it's mainstream and using it doesn't automatically become a suspicious activity.