Checking your cPanel webmail
After adding email accounts, you can check them through cPanel’s built-in webmail clients (Roundcube, Squirrel Mail, and Horde Mail) by going to the following:
http://your domain name/webmail
After logging in, you have to choose which webmail client you want to use. Choosing is just a matter of preference, but you can view their differences in cPanel’s documentation, Which Webmail Application Should I Choose?