If you want to import MBOX files into Yahoo Mail instantly, the easiest way is to use 
eSoftTools MBOX Converter Software. Yahoo Mail does not support direct import of MBOX files, so you need to first convert them into a compatible format like EML. This software allows you to convert multiple MBOX files to EML format in bulk, preserving all emails, attachments, sender/receiver details, subject lines, and original formatting. After conversion, you can easily import the EML files into Yahoo Mail using the standard import options. 
The tool supports all MBOX-based email clients like Thunderbird, Apple Mail, Eudora, and more. It also maintains the original folder structure during conversion, ensuring your emails remain organized. eSoftTools MBOX Converter works with all Windows versions and provides a free demo to export 25 emails per folder, so you can test it before buying. This is a fast, safe, and reliable solution to import MBOX files into Yahoo Mail without any hassle.
Read More:- Import MBOX File into Yahoo Mail