Alternativer til SlideMail til Self-Hosted med open source-licens

• Self-Hosted
  Alle 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)
• Open Source-licens
  Enhver licens Gratis licens Open Source-licens Kommerciel licens