If you are looking for a tool that can back up Yahoo emails without any hassle, I would definitely recommend the GainTools Yahoo Backup Tool. I have used it myself and the interface is quite clean. It lets you save emails directly from your Yahoo account in formats like PST, MBOX, and EML, and the best part is that it does not require Outlook. You can take folder-wise backups and save attachments as well and the formatting of the emails remains exactly as it appears in Yahoo. You can test it first by backing up a limited number of emails from each folder in the trial version. I think it is a reliable tool for personal and small business use.
Read More: https://www.gaintools.com/backup/yahoo/