Welcome to Firefox for Android Add-ons.
Add extra features and styles to make Firefox for Android your own.
CloseReview for Mark All Read:WE by Andrew
Rated 1 out of 5 stars
If you want a 'Mark All Read' button that works for Thunderbird 78+ install https://addons.thunderbird.net/en-GB/thunderbird/addon/next-unread-group/ and change the value for mailnews.nav_crosses_folders in about:config from 1 to 2.
This review is for a previous version of the add-on (1.1).To create your own collections, you must have a Mozilla Add-ons account.