I've found that when user (or agent) opens a ticket mail's link from Google Apps always ask for login credentials in new browser's tab (both Chrome and Internet explorer).
As using Apps need to use OpenID and manually enter domain or email, being unable to tick "remember in this machine" in every access
When eStreamdesk is open from Google Apps menu then the session is transfered correctly an no login necessary. For agents is usual to keep open in a tab in this way but for users is a bit annoying.