All ShoutCMS mail accounts can be accessed using WebMail even if you are also using an email client. This article explains how to use your browser to access your email via WebMail.
Launch your web browser and type in http://webmail.yourdomain.com. Do not include "www." in the URL.
You will see a login dialogue asking for your email address and password. Enter in your full email address beside the envelope icon and your email password into the password field. Click the Sign In button.