I'm not a security expert so my ability to explain is limited, but no, emails have long used encryption protocols like SSL to prevent such problems. However, your email provider may scan and read your emails. That's not much different than a text message service reading those messages, but you can choose your provider. From what I can tell proton.me is the way to go for resolving that issue - they provide encryption which prevents their own machines and employees from being able to read your messages and other data. Otherwise, your email is basically as secure as your passwords are.