\usemodule[letter]
\starttext
\setupletter
[toname={President George W. Bush}, 
toaddress={Office of George W. Bush\\Post Office Box 259000\\Dallas, Texas 75225-9000}] 
[fromname={Russ Urquhart},
fromaddress={4645 Portrait Ln\\Plano TX 75024}]
[signature={Russ Urquhart}]

\startletter
Dear President Bush,

I thought it important to take this opportunity.

\stopletter
\stoptext