I assume the person to whom you are replying was thinking more along the lines of end-to-end encryption. Email is very rarely end-to-end encrypted, and none of

I assume the person to whom you are replying was thinking more along the lines of end-to-end encryption. Email is very rarely end-to-end encrypted, and none of its standards relate to end-to-end encryption so you have to do it with other methods which are notoriously difficult to use correctly.