If you are looking to import MBOX to Office 365, users can use the Shoviv MBOX to Office 365 Migration Tool. It is designed to simplify MBOX mailbox migration directly into Office 365 accounts while maintaining complete folder hierarchy, email formatting, and metadata integrity.
Key advantages of Shoviv include:
Directly import MBOX to Office 365  with secure modern authentication
Supports multiple MBOX files from Thunderbird and other email clients
Preserves attachments, contacts, and folder structure accurately
The incremental migration feature avoids duplicate mailbox items
Option to migrate large mailboxes without size limitations
User-friendly interface suitable for both technical and non-technical users
Compared to manual migration, Shoviv provides a much smoother and more reliable experience, especially for bulk migrations and business environments.

If you are still lookin for a solution to move data from MBOX file to Office 365 account then you can go with MailsDaddy MBOX to Office 365 migration tool. This GUI application has lots of features and functions that helps each level of user to open data in Office 365 account. With the solution, user can migrate MBOX file to Office 365  primary, in-place archive and group mailbox. The software also offers preview, batch migration, filter conversion, csv upload facilities to initiate conversion instantly.