Blue Mail is a free, but incredibly powerful email client. It is compatible with almost every email provider including Gmail, Outlook and Yahoo Mail. The app has a simple interface. It can connect with an unlimited number of email accounts from different providers. Blue Mail offers a unified interface and a set of smart settings to let you customize your experience. Some of its features include widgets, color coding, and the ability to lock up private emails. There is a reason it has a 4.6/5 rating on the Play Store. Blue Mail is undoubtedly one of the best Android apps for email management.