Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
Simple Calendar - A simple calendar with events (optional recurring and reminders), week numbers and a customizable...
Evolution - Apps/Evolution - GNOME Wiki!