Yes, emails sent outside of your organization
will still be stored encrypted within
ProtonMail; however, in order for it to be sent
end-to-end encrypted you will need to use our
“Encrypt to Outside” feature which you can read
more about
here. We recommend using end-to-end encryption for
all messages that you want to maintain full
control of the contents (including the ability
to set an expiration date on the message).