Alternativa SlideMailu za Ruby s komercijalnom licencom

• Ruby
  Sve platforme Windows Mac Linux Chrome OS Android iPhone Apple Watch Android Wear iPad Android Tablet Windows S Web Self-Hosted BSD Haiku PortableApps.com Slack F-Droid Chrome Ruby Gmail Cloudron Amazon Echo (Alexa Voice Service) PureOS (Purism)
• Komercijalna licenca
  Bilo koja licenca Besplatna licenca Licenca otvorenog koda Komercijalna licenca