\usemodule[letter][extension=optimize]

\mainlanguage[de]

\setupletterstyle
  [option]
  [whitespace=line,
   optimize=yes,
   ]

\setupletter
  [toname={Vodafone Kabel Deutschland GmbH},
   toaddress={Kundenservice\\99116 Erfurt}]

\setupletter
  [fromname={Hanna Musterfrau},
   fromaddress={Irgendwostr. 18\\99999 Nirgendwo}]

\setupletter
  [name={Joe User},
   date=\currentdate]

\setupletterstyle[reference][list={name,date}]

\starttext

\setupletter
  [subject={Reason},
   opening={Sehr geehrte Damen und Herren,},
   closing={Freundliche Grüße},
   signature={Paul Menzel}]

\startletter\relax
\dorecurse{4}{\input ward\par}
\stopletter

\stoptext