If you need to migrate MBOX files to Office 365,
CloudXena MBOX Converter is one of the easiest tools to use. Just install the software, add your MBOX files or folders from Thunderbird, Apple Mail, or Gmail, and preview the emails. Select Office 365 as the target platform, log in with your credentials, use filters to pick only what you want to transfer, and click Convert. The tool preserves formatting, attachments, and folder hierarchy, so your mailbox looks the same in Office 365 after migration.