Removes all messages marked with 'Deleted' flag from the currently selected mailbox and unselect mailbox.
This method permanently removes all messages that have the 'Deleted' flag set from the current (selected) mailbox, and then closes (deselect) the mailbox.
This method returns a result code; 0 indicates success, while a non-zero error code indicates that this method encountered an error during its execution. If an error occurs, the GetLastError() method can be called to retrieve the associated error message. (Note: This method's result code can also be obtained by calling the GetLastErrorCode() method after it returns.)