The normal method for accessing your webmail is by navigating to "yourdomain.com/webmail" and logging in. If you want to access email accounts which you have administrator access to, you can do it through cPanel.
- Log in to cPanel.
- Under the Email section, click "Email Accounts".
- Find the account you wish to use, and click "Check Email" next to it.
- Click "Go to Secure Webmail Login".
- Select the mail client to use. The choices are Horde or Roundcube.