Follow these steps to set up Yahoo! Email forwarding:
Click the gear icon in your inbox. Choose More settings.
Choose Mailboxes and click on your Yahoo account.
Choose your Yahoo account.
In the Forwarding section, enter your Text App forwarding address (here you can find your Text App forwarding address). Click Verify.
Go to your Text App dashboard. Open the message from Yahoo (attention: might be in the SPAM folder).
Click the link in the message. Once the page is loaded, click Verify.
As of January 1, 2021, automatic forwarding of emails is no longer available for free Yahoo Mail users.
Learn more about the changes in the Yahoo! automatic forwarding of emails.