Mail client is a program designed to work with e-mail (writing, sending, receiving and storing e-mails). E-mail can also be used using a browser, but this is not very convenient if you have several accounts, i.e. several mails. Therefore, for convenience, a special mail program is usually installed on the computer, in which all accounts are configured, and used to work with e-mail. In addition to the built-in media player in Windows 10, there is also a built-in mail client, it’s called Mail, but many people, like the media player, don’t like it or they just aren’t used to it. Therefore, most users use a third-party mail program, i.e. mail client. Thus, the mail client is also a very useful and necessary program for Windows 10. Some of the most popular email clients include: Mozilla Thunderbird The Bat!