Mac Mail addresses not showing in Contact App

Hello! So, I know I have many email addresses that are somehow stored in my Mac Mail because they populate as I type the beginning of the address. But, when I open the Contacts App these addresses do not show in the individuals contact. How do I get these addresses from Mac Mail to my Contacts app?

The goal is to send a group email to all of my business contacts by selecting their name/email address from a list. I think I can do that from Contacts if the emails are there. But if I were to try to do that in Mac Mail now I believe I would have to type each email address.

Many thank yous! Stephen