Sharing emails that are attached to a Contact/Potential

I just discovered that emails that I send to a contact and .bcc zoho indeed show up on their record and potential that they are associated with. That's the good news. I also learned that a new sales rep who has access to that record doesn't see any of those emails. Why is that? How can I make sure that everyone that has authority to work with that contact and potential sees the entire email chain associated with it?

TIA for your response.

Sam