User restrictions

Hi Tom,
I am the Super Admin and have several accounts on our account for which I manage.
If I have already restrictted the user to only have view contacts and companies (e.g., no edit or delete), how can I restrict HubSpot not to add a contact when the user sends an email via Hubspot?

Would the only way be to not add the Gmail option on HubSpot?

How do I restrict any contact or company to additions in addtion to edits and deletions?
Thanks!