Alternativa PlanPlusOnlineu za Microsoft Office Outlook z licenco odprtokodnega vira

• Microsoft Office Outlook
  Vse platforme Windows Mac Linux Android iPhone iPad Web Self-Hosted Software as a Service (SaaS) Windows Mobile Microsoft Office Outlook Chrome Microsoft Office Suite
• Open Source licenca
  Vsako dovoljenje Brezplačna licenca Open Source licenca Trgovsko dovoljenje