To prevent future emails from the same sender from going to the Spam folder automatically, you need to mark the email as "Not Spam" 

  1.  Navigate to Yahoo Mail, log in to your account.
  2.  Click the Spam folder.
    • If you don't see the "Spam" folder, click More below the "Sent" folder.
  3.  Select the email.
  4.  Click Not Spam at the top of the page.
    -The email will return to your Inbox.