Rated 5 out of 5 stars
Very nicely designed buttons and useful functionality. Developer reacts fast to inquiries!
If anybody is searching for a pure "Mark All Read" functionalty with only one click, here is how he explained me to do it:
The "Mark All" button marks all messages in a folder or newsgroup as read an then takes you to the next unread message.
To make this work without a confirmation you have to set mailnews.nav_crosses_folders in about:config to 0.
Thanks for this Addon!