If you are using Gmail: here are the steps:
You click on the mail receive by the two emails above and open the mail.
You go on the top right end of your message and click on the button "More"
And then scroll down until you reach: Add the user to your contact list.
You should receive a message in the middle of the screen confirming the action
To be certain that the email address has been added, go to your contact list
Otherwise, you might have to add the email addresses manually by clicking on the red + button (bottom right)
See you soon, YoungMi 😀