With the help of the Shoviv MBOX Converter tool, you can easily export your Thunderbird emails into PST format. Once you get your PST file; import it into Outlook via the Outlook Native Import/Export option.
Read more: https://www.shoviv.com/blog/export-emails-from-thunderbird-to-outlook-2016-2019/
If you want to import your emails from Outlook PST file to your Gmail account then, I would like to suggest the Shoviv Gmail backup and restore tool. This tool effortlessly uploads your emails from PST to your Gmail account in no time. Apart from PTS import, you can also import Outlook OST (Offline Storage Table) files into Gmail.
Read more: Import PST file to Gmail
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