Rated 2 out of 5 stars

Unfortunately, ReminderFox has stopped working since a recent Thunderbird update. Not only have my dates and reminders gone, but I have also lost confidence in ReminderFox so I will look for an alternative.

This review is for a previous version of the add-on (2.1.6.6). 

Reminderfox also with the most current version 2.1.6.9 only supports Thunderbird up to version 60.*
TB68 etc isn't supported.