After your deleted emails have been removed from your Trash folder, you can still restore them. You will have to download them to another account or forward them to a secondary email address before you can restore them. Once you have done this, you can fill out the Yahoo! Mail Restore Help Form to retrieve your email. When you receive a confirmation from Yahoo, you will be able to view the restored email and download it.

Must Read : https://emailscrunch.com/how-to-recover-deleted-yahoo-mails/