How to Access Email Accounts Through Any Web Browser
First, you need to login to cPanel and click on the Email Accounts icon located in the MAIL section.
Then click Access Webmail on the necessary email account
The first time that you log in to Webmail, the interface will display three webmail applications: SquirrelMail, Horde, and RoundCube.
Click Set as Default to automatically open Webmail in the selected application each time that you log in.