\documentclass[12pt]{letter}
\usepackage[businessenvelope]{envlab}
\makelabels
\begin{document}
\startlabels
%s
\end{document}

\documentclass[12pt]{letter}
\usepackage[noprintbarcodes,nocapaddress,norotateenvelopes,personalenvelope]{envlab}
\SetEnvelope{5.75in}{4.4375in}
\makelabels
\begin{document}
\startlabels
%s
\end{document}

Make addresses look less business-like, set envelope size
Make addresses look less business-like, set envelope size
