Open Source Document Management System | OpenKM

Hi all!
I am using OpenKM 6.3.2 Community on Ubuntu 14.04.5 and I have two questions:

• - Is there a way to configure a user so that he can view the document history and download the versions in it while not being able to restore a version or delete the history?
  - I have enabled the profile option "Notify external users", how does this work? I don't get the option to notify anyone other than the users already registered in the system.

Thank you in advance!

About notify to externals, should appears an input below the OpenKM users lists for adding mail address.
About history, the users can not delete an specific document version, only can compact ( means get the last and delete the others ). About restore to previous version if you do not have a button "restore" ( only will appears if you have several versions ) take a look if there's a contextual menu, I do not remember how it goes with community version ( add a screenshot for it here ).