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.
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.
Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
Spark Mail - Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues