Alternativy k MailTracker pro Boomerang s licencí open source

• Boomerang
  Všechny platformy Windows Mac Linux Chrome OS iPad Web Firefox Chromium Vivaldi Browser Microsoft Office Outlook Chrome Gmail Dropbox Streak CRM Yesware Boomerang Zeplin
• Licence Open Source
  Jakákoli licence Bezplatná licence Licence Open Source Komerční licence