How to add an "Attendee" and get rid of the unnecessary options when adding an attendee to Decision Meeting Workspace?

Hello Community

    Decision Meeting Workspace has a section name "Attendees".

    To add an attendee you click the link that says "Manage Attendees".

    Then on the ribbon there is a tab labeled "List Tools" which contains
2 option "Items" and "List".

    If you click Items option and then click New Item when the tooltip appears
you can type the name of the Attendee.

    The problem is that after it finds the user you cannot save the users name as
an attendee if the user doesn't have an email address, the error states:

    "User <domain\username> does not have an e-mail address."

    The other problem is that the users shouldn't be able to select the "List" option
because all of the items on the ribbon confuses them.

    So the question is how do you save a user as an attendee if they don't have an
email address when you select "Items" and how to you prevent the user from accessing the
"List" option (any remedy would be good whether you can delete the "List" or disable it somehow)?

    Thank you
    Shabeaut