How to Backup Yahoo mail emails?
To back up your Yahoo Mail emails, download and install the Yota Yahoo Backup Tool on your computer. Open the software, go to Email Accounts > Add Account, and log in with your Yahoo email credentials. Then, click on the Export button and choose the file format you want, such as PST, PDF, MBOX, or EML. Finally, select a location on your computer to save the backup and click Save. Your Yahoo emails will be downloaded quickly and safely.
https://yotasoftware.com/yahoo-backup/