Hiding this feed type from some users

We have a requirement to restrict visibility of the emails sent by some users from the rest of our advisors,   is this possible?

I have searched for the system location of this record but have been unable to locate it.

I searched in Tasks, Task History, Account Feed, Feed Items, - We have no Email object.

Our implementation seems to use Office 365 Outlook integration but also uses EAC which seems to be generating these messages.

Any Ideas where this record is stored, or if it can be removed from the feed?

Ideally I would like the feed item to relate to an opportunity rather than the contact and account.