@richardbrand you are conflating all these issues, like SMTP and SSL, all major email providers encrypt the messages, meaning no one else can decrypt it and read it during the transportation of the packages.
If it wasn't the case all hackers would be billionaires but at least multi-millionaires.4
Email is usually sent over the internet in plain text
No it is not. It is encrypted. If it was sent in plain text, you would have 99 out of a 100 politicians blown into a zillion pieces by scandals.