Rated 4 out of 5 stars

4 stars for good concept but for me it is not working. It counting all mails as "Received". Not recognize "Sent" mails at all - sometimes show few random mails as "Sent". I have near 50000 mails so maybe it is to huge for database of this extension. "Sent" mails are about 7000. Of course I'm using the newest Thunderbird 91.

This review is for a previous version of the add-on (1.8.0). 

Many thanks for your feedback! 50k isn't too huge at all. Do you have your email identities configured in your Thunderbird account settings? Or if you are using a local account: Do you have all identities configured in the add-on options?
Please issue a bug report if you suspect wrong behaviour and I'll take a look at it.
https://github.com/devmount/third-stats/issues/new?template=bug_report.md