No one can directly export Thunderbird mailbox to Office 365 cloud. Therefore we suggest MailsDaddy Thunderbird to Office 365 Migration Tool to migrate bulk or selective Thunderbird email files to O365 account without any problem. All you need to do is add the login ID and password of the Office 365 account and start the conversion process. All Windows versions are well suited to use this program, including Win 10. The free version of the software converts 20 emails from each mailbox.

More Info- https://www.mailsdaddy.com/thunderbird-to-office-365-migration/