The best Thunderbird to Office 365 converter is the eSoftTools Thunderbird to Outlook Converter software. This is an amazing software that exports your Thunderbird to a PST file. It can auto-load configured Thunderbird MBOX for migration and simply convert it to a PST file. It can also give the user a batch conversion facility. There is no restriction on the size of the Thunderbird file for conversion. It can perform very well with all versions of Windows up to 10 and all editions of MS Outlook 2019, 2016, 2013, 2010, 2007, & 2003.
For more info- Thunderbird to Office 365 converter
For more info- Thunderbird to Office 365 converter