UpNote - A beautiful and clean cross-platform app for notes organizer
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Notesnook - Notesnook is a simple and private note taking app that keeps your notes organized and synced on your phone, tablet and computer.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
todoZero - A powerful to-do and note app for busy people.
eM Client - eM Client is a fully-featured email client for Windows and macOS with a clean and easy-to-use interface. eM Client also offers features for calendars, tasks, contacts, notes, and chat.