Kopfzeile bei Briefen mit scrartcl und scrletter

\RequirePackage{filecontents}
\begin{filecontents*}{DIN5008A.lco}
%
% This is file `DIN5008A.lco'.
% Copyright (c) 2015 Markus Kohm [komascript at gmx info]
% 
% This file may be distributed and/or modified under the conditions of
% the LaTeX Project Public License, version 1.3c of the license.
% The latest version of this license is in
%   http://www.latex-project.org/lppl.txt
% and version 1.3c or later is part of all distributions of LaTeX
% version 2005/12/01 or later.
%
% This work has the LPPL maintenance status "maintained".
%
% The Current Maintainer and author of this work is Markus Kohm.
%
\immediate\write17{^^J%
+----------------------------------------------------------------------^^J%
| WARNING (`DIN5008.lco'):^^J%
+----------------------------------------------------------------------^^J%
| YOU SHOULD NOTE, THAT THIS IS NOT AN EARLY BETA RELEASE!^^J%
| THIS VERSION IS INTENDED TO BE USED FOR TESTING ONLY!^^J%
| USAGE FOR PURPOSES OTHER THAN INTENDED IS DANGEROUS!^^J%
| DON'T EXPECT ANY SUPPORT FOR THIS VERSION!^^J%
+----------------------------------------------------------------------^^J%
}
\ProvidesFile{DIN5008A.lco}[2015/02/16 v0.1-beta letter-class-option]
\LoadLetterOption{DINmtext}
\KOMAoptions{fromalign=locationleft,addrfield=topaligned,refline=narrow}
\@setplength{firstheadhpos}{25mm}
\@setplength{firstheadwidth}{100mm}
\@setplength{specialmailindent}{5mm}
\@setplength{specialmailrightindent}{0pt}
\@setplength{toaddrindent}{5mm}
\@setplength{lochpos}{-125mm}
\@setplength{locvpos}{32mm}
\@setplength{locwidth}{75mm}
\@setplength{refvpos}{\dimexpr\useplength{tfoldmarkvpos}-32pt}
\@setplength{refaftervskip}{8.46mm}
\@newplength{specialmailheight}
\@setplength{specialmailheight}{12.7mm}
\newcommand*{\textareabydin}{%
  \areaset{165mm}{233mm}%
  \setlength{\oddsidemargin}{\dimexpr 25mm-1in}%
  \setlength{\evensidemargin}{\dimexpr 20mm-1in}%
}
\renewcommand{\backaddr@format}[1]{\hspace*{\useplength{toaddrindent}}%
  \parbox[t][\useplength{backaddrheight}][t]%
         {\dimexpr\useplength{toaddrwidth}-\useplength{toaddrindent}}%
         {\strut\ignorespaces #1\unskip\strut}%
}
\renewcommand{\specialmail@format}[1]{%
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         {\dimexpr\useplength{toaddrwidth}-\useplength{specialmailindent}-\useplength{specialmailrightindent}}%
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}
\setkomafont{specialmail}{\sffamily\fontsize{10pt}{12pt}\selectfont}
\setkomafont{backaddress}{\sffamily\fontsize{8pt}{10pt}\selectfont}
\setkomafont{addressee}{\sffamily\fontsize{10pt}{12pt}\selectfont}
\setkomafont{fromname}{\sffamily\fontsize{10pt}{12pt}\selectfont}
\setkomafont{fromaddress}{\sffamily\fontsize{10pt}{12pt}\selectfont}
\setkomafont{refvalue}{\sffamily\fontsize{10pt}{12pt}\selectfont}
\let\raggedsignature\raggedright
\end{filecontents*}

\documentclass[fontsize=12pt,fromphone,fromfax,fromemail]{scrartcl}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage{lmodern}
\usepackage{scrletter}
\LoadLetterOption{DIN5008A}
\textareabydin




\setkomavar{backaddress}{Rücksendeadresse}
\setkomavar{yourref}{abc-01}
\setkomavar{yourmail}{2013-04-23}
\setkomavar{myref}{mihh-00}
\setkomavar{fromname}{Max Muster}
\setkomavar{fromaddress}{Musterhaus 1\\99999 Musterstadt}
\setkomavar{fromphone}{040~1234-5678}
\setkomavar{fromfax}{040~1234-7890}
\setkomavar{fromemail}{max.muster@invalid.invalid}
\setkomavar{date}{2013-04-30}

\usepackage{mwe}

\begin{document}

\setkomavar{specialmail}{VZ3\\VZ2\\VZ1}



\begin{letter}{AZ1\\AZ2\\AZ3\\AZ4\\AZ5\\AZ6}
\opening{Sehr geehrte Damen und Herren}
\Blindtext
\closing{Mit freundlichen Grüßen}

\end{letter}

\end{document}

\begin{center}
\begin{tiny}
\begin{tabular}{|m{2cm}|m{2,5cm}|m{2,5cm}|m{2,25cm}|m{2cm}|m{2cm}|}
  \hline 
  \texttt Nr. &\texttt Dokumenttyp & \texttt Beweisart & \texttt Aussteller (Urkunde)& \texttt Datenart & \texttt Datenart    \\   \hline
  PU-1.\textsubscript{ZISA}& Beweismittel & Privaturkunde  & ****& Aussage & Aussage  \\ 
  \hline
\end{tabular}
\end{tiny}
 \end{center}