Alternativas ao NeutronMail para Software as a Service (SaaS) com licença de código aberto

• Software as a Service (SaaS)
  Todas as plataformas Windows Mac Linux Android iPhone Android Wear iPad Web Self-Hosted Software as a Service (SaaS) PHP JavaScript Windows Mobile Java Mobile S60 Docker Cloudron OpenPGP Kubernetes S/MIME OpenShift DAVdroid
• Licença Open Source
  Qualquer licença Licença gratuita Licença Open Source Licença comercial