Tagging multiple threads - astroidmail/astroid GitHub Wiki
In the thread index view, you can tag multiple threads by marking them using t, then press ; (semicolon). This would show a horizontal bar at the bottom, along with a bunch of possible actions and their keyboard bindings. Press one of the bindings to run the corresponding action. For e.g., press R to toggle unread tag, S to toggle spam tag, a to archive, etc.