How to apply different MAO actions to a variety of messages in quick succession
Mail Act-On gives you the time saving ability to use the keyboard to select and apply a variety of different actions to different messages in quick succession. To enable this feature involves two main steps: locking the Act-On window and then shifting control between the Act-On window and the message window.
Locking the Act-On window
You lock and unlock the Act-On window (toggle the window) by tapping the same menu key used to display the window. The bottom of the Act-On window tells you which key to use.
Control

You can now use the up and down arrows to navigate for a desired Keystroke action. *Note that the control is in the Act-On window.
Use the forward arrow to apply your action to a selected message. *Note that the control is now in the message widow. You can now use the up and down arrows to navigate the message window, and continue to apply the keystroke action in quick succession to further messages. Alternately, use ACT-On keystrokes to select and apply a different action to the message selection.
Use the backward arrow to move control back to the Act-On window to select another action. Use the forward arrow to apply the action to a selected message and return control to the message window.
These actions will become more fluid with a little practice.
Tap the escape key to hide the Act-On window.