具有开源许可证的Haiku版Columba的替代方案

• Haiku
  所有平台 Windows Mac Linux Chrome OS Android iPhone Apple Watch Android Wear iPad Android Tablet Windows S Web Self-Hosted BSD Xfce Haiku PortableApps.com Slack F-Droid Ruby Gmail GNOME Cloudron Amazon Echo (Alexa Voice Service) OpenPGP PureOS (Purism) S/MIME
• 开源许可证
  任何牌照 免费许可证 开源许可证 商业牌照