If you send an encrypted email from protonmail.ch to someone who uses another email provider, he get's a notification email with a link that does just that.
However the recipient should know the password to see and reply to the email.
Mac OS X is a necessity for some users specially in media related industries and not only. It also manages to offer most of the software regular users want and Apple makes a profit from Mac sales.
As hardware and software Windows Phone is by no means a failure. Nokia creating beautiful devices with good cameras and the fact that even in low specs WP runs snappy is promising and helped a lot to achieve this 4%. But WP is not yet profitable.
One of the reasons Windows Phone is considered to be a failure is that it hasn't managed to create an ecosystem where most popular apps exist at the three years of its existing form (counting from Windows Phone 7).
However the recipient should know the password to see and reply to the email.