An email client is a software application that allows users to access, manage, and send emails from their computer, tablet, or smartphone. It provides a user interface that allows users to view and organize their email messages, and can be standalone applications, web-based applications, or mobile applications. Email clients can also provide additional features such as calendar integration, contact management, task management, and email filtering.

Email clients work by using email protocols to connect to mail servers to send and receive emails. When a user wishes to create and send an email, the email client will handle the task and is usually set up automatically to connect to the users mail server, which is typically either a Mail Submission Agent (MSA) or a Mail Transfer Agent (MTA) . The email client which uses the Simple Mail Transfer Protocol (SMTP) creates an authentication extension, which the mail server uses to authenticate the sender.

The main difference between an email client and webmail is that an email client is a software program that is installed on the users device, while webmail is accessible through multiple browsers. Email clients allow users to manage their emails more efficiently by providing a central location to view and organize emails, while webmail is a web-based email service that allows users to use email features using their website browser.

Some examples of email clients include Microsoft Outlook, Mozilla Thunderbird, Apple Mail, Gmail, and Proton Mail. The benefits of using an email client include the ability to manage emails more efficiently, customize the email client with different apps and features, and access emails from different email accounts in one place.