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

myMail - myMail is the smart email app for managing all your accounts on iOS and Android.

mlist - Email newsletters, outside of the inbox

Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.

TL;DR Email - Send short emails & read emails as fast as you read Facebook

Mailbutler - Mailbutler adds lacking functionality to email clients and increases your productivity