When new mail is received, this animated icon appears in the System Tray (or "Notification Area") at the bottom right of your screen.
This is useful if you wish to make a quick check of what new mail has been received, eg if you are working on something else and do not wish to take the time to make a detailed check.
A right-click will restore MailCOPA and produce a menu:
•Clear Status - simply clears the icon from the Tray.
•Show Mail Received - opens the Mail Received window.