If you log into webmail directly from your cPanel login, you are only going to be able to access the default/main email account. There should be no mail in that account.
To access your other email accounts, you MUST log into webmail via http://(servername).genwebserver.com/webmail OR http://www.yourdomain.com/webmail (replace "yourdomain.com" with your actual domain name).
From there, you must use the FULL EMAIL ADDRESS you are trying to log into as the email username.
