Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
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
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Express Mail - Best mobile email app for Salespeople
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
myMail - myMail is the smart email app for managing all your accounts on iOS and Android.