\documentclass[12pt,a4paper]{letter}
\begin{document}

\address{1234 Avenue of the Armadillos \\
         Gnu York, G.Y. 56789}
\signature{R. (Ma) Dillo \\ Director of Cuisine}

\begin{letter}{G. Natheniel Picking \\
               Acme Exterminators \\
               Illinois}

\opening{Dear Simon,}

I'm afraid that the armadillo problem is still with us.
I did everything that you recommended but we have seen little improvement.
Can you suggest more drastic action?


On an entirely different and unrelated note, let me thank you for 
introducing me to \LaTeX --- its wonderful!  My whole life has changed as
a result.  I expect my company will shortly turn a profit for the first
time;  the share-holders are over-the-moon --- their money is no longer
going to Redmond.


\closing{Best Regards,}
\cc{Jimmy Carter\\Richard M. Nixon}
\end{letter}

\end{document}