[otrs] Disable all outgoing mails ?

Hi, i am currently installing OTRS for a Typo3 single-signon demo environment. I want to disable some functions of OTRS and already got rid of 'Logout' and 'change password', but i dont know which is the best way to disable all outgoing mail traffic (i want to show single-signon and dont want the users to use otrs ). mfg Dennis