In the summary view, how can I prevent users from seeing other user's emails?

I am using the Sugar CRM community edition 6.5.14. I have given all users viewing rights to all contacts and opportunities. Under the history section, they can see what emails have been sent, but they can't click through and read the emails from others, for privacy reasons of our customers. I can perfectly manage this with the role settings.

However, if they click the View summary button (in the History section), they can read through all the emails, also the ones sent or imported by others. Is there a way to prevent this? Or, as an alternative, can I remove the View summary button?