Login as a user who is a member of Site Administrators group
Go to @@overview-controlpanel
Click on "Mail" or skip 2 and go straight to @@mail-controlpanel
Result
Insufficient Privileges
You do not have sufficient privileges to view this page. If you believe you are receiving this message in error, contact the site administration.
Expected
Site Administrators should have permission to use the mail control panel.
Any control panel that a certain user group or role does not have permission for should not be listed in @@overview-controlpanel.
Plone 5.0.3-pending
Result
Expected