So you can not get to the scroll bar or the "red X" because your message
window is opening off-screen to the right? is that what yiou were trying to
say here?
Grab the "Title bar" of the message and drag it left - point the mouse on
that top title area and hold the left button down and drag the mouse left -
should pull your message across the screen to the left. If it still won't
"fit", you may have to move the right side border inward - hover the mouse
over it until it turns into a double-headed arrow, hold the left mouse
button in and drag that border inward (right). Then go back and try
dragging by the title bar again. Eventually you should reach that far right
side of the message. Did you by any chance change your desktop
personalization to a larger display size? That will cause mail to open
"off-screen".