\documentclass{scrartcl}
\usepackage{scrletter}
\begin{document}
\begin{letter}{}
\tableofcontents
\section{1}
\tableofcontents
\subsection{a}
\subsection{b}
\section{2}
\tableofcontents
\subsection{A}
\subsection{B}
\end{letter}
\end{document}
Only the first tableofcontents is printed. The second and third shall only print the tableofcontents for the current section. How do I achieve that?