You can use the Mozilla Thunderbird Backup Tool to easily migrate from Thunderbird to Office 365. It allows you to export Thunderbird emails directly to Office 365 without any data loss. The tool preserves folder hierarchy, email formatting, and attachments during migration. Plus, it supports multiple saving options like PST, MBOX, EML, PDF, and more, giving you flexibility for backups. Its simple interface makes the process smooth, even for non-technical users.