If you want to import MBOX file directly into Yahoo Mail, there is no built-in option for it, but eSoftTools MBOX Converter software can do this easily. This tool scans MBOX files and gives you the option to export them to a supported format or directly to an IMAP account. Install the software, select the MBOX file, check the preview and start the export by choosing a Yahoo Mail account via IMAP credentials. This process safely migrates emails, attachments and folder structure without data loss.

Read More:- Import MBOX File into Yahoo Mail