What is an Email Client?

An email client is a program or web application that is designed to receive, write, send, and keep your email messages. 

This video produced by GoDaddy defines an email client, explains its role, and sheds light on the way it functions:

Before someone starts using an email service, usually, the email client requires several settings. These settings include an email address, password, POP3/IMAP and SMTP address, port number, email alias, and other related preferences.

The most popular email clients are Gmail, Apple Mail, Outlook, Yahoo!Mail and Hotmail. Statistics in the graph below show the market share of the world’s most used email clients in 2015. During this period, Apple iPhone accounted for 32.2% of email opens, and Gmail accounted for 15.2% of email opens.