Log in as admin user (let us say id=5) and try to edit messaging setting for another user (let us say id=6):
1. as the admin user go to /message/edit.php?id=6&course=1
2. save the form
Messaging settings of the user id 6 are saved and I am redirected to the same page
The setting as saved as for the current user (id=5) - including the email addresses and Jabber IDs and the browser is redirected to the page of messaging setting of the current user.