具有免费许可证的Microsoft Exchange Server版WhenIsGood的替代品

• Microsoft Exchange Server
  所有平台 Windows Mac Linux Chrome OS Android iPhone Windows Phone Blackberry iPad Android Tablet Web Self-Hosted Software as a Service (SaaS) PHP jQuery Windows Mobile Slack Microsoft Office Outlook Chrome Adobe Flash Player Google Calendar Google Apps Microsoft Exchange Server Apple Calendar
• 免费许可证
  任何牌照 免费许可证 开源许可证 商业牌照