It has numerous higher costs, from special email software to the social pain of getting your friends to also use it. With 'special email software' do you mean

It has numerous higher costs, from special email software to the social pain of getting your friends to also use it. With 'special email software' do you mean not-webmail? Outlook is still around in many companies, where your colleagues are already connected. IIRC there's a PGP plugin.