Alternativa nPOPuku za S/MIME sa licencom otvorenog koda

• S/MIME
  Sve platforme Windows Mac Linux Chrome OS Android iPhone Windows Phone Apple Watch Android Wear iPad Android Tablet Windows S Web Self-Hosted Firefox Opera Chromium BSD Xfce Haiku PortableApps.com Chrome Ruby Gmail Adobe AIR GNOME Cloudron OpenPGP S/MIME
• Licenca otvorenog koda
  Bilo koja licenca Besplatna licenca Licenca otvorenog koda Komercijalna licenca