Most users nowadays have high-speed internet connections and therefore an explicit progress bar for sending messages was no longer necessary in Version 8.

However, if you still want to monitor the progress of your sent emails and updating folders, you can open the Operations window by going to Menu > Operations.

If you want the Operations window progress bar to always be displayed as you send and receive messages, you can turn on this feature under Menu > Settings > General > General > Operations Window and select the box for Show window on send and receive.