How do you link an email to a potential?

How do you link an email to a potential?

Hi,

I want to link some emails sent from a contact to a Potential ( I hate the email add-on) , the problem is that it is grabbing all the emails sent by this contact. This contact makes a lot of orders, so sometimes we have 3 Potentials with him and it is getting hard to track emails sent by us to him in order.

How can I chose what emails to link for each Potential?

SR,