\documentclass[a6paper,landscape,7pt]{scrartcl}
\usepackage[ngerman]{babel}  % German umlauts
\usepackage[utf8]{inputenc}  % German umlauts
\usepackage{hyperref}  % seems to be important for multicols
\pagenumbering{gobble}  % disable page numbering
\usepackage{multicol}  % split page in two parts
\usepackage{helvet}
\renewcommand{\familydefault}{\sfdefault}
\usepackage[margin=0.2cm]{geometry}
\usepackage{parskip}

\setlength\columnseprule{.4pt}
\begin{document}
\begin{multicols}{2}
    Skyline of Pittsburgh, Pennsylvania\\
    {\small Photographer: Max Mustermann}
    \columnbreak\par
    \vspace*{0cm}
    \hfill\framebox(40,50){\scriptsize Postage}\hspace*{1cm}\par
    \vspace{0.2\textheight}
    \rule{6.0cm}{0.01cm}\vspace*{1cm}\\ % Name
    \rule{6.0cm}{0.01cm}\vspace*{1cm}\\ % Street + Nr
    \rule{2.2cm}{0.01cm}\hspace*{0.2cm}\rule{3.6cm}{0.01cm}\vspace*{1cm}\\ % zip code + town
    \rule{6.0cm}{0.01cm}\\ % country
\end{multicols} 
\end{document}