You get what you pay for. I bear no personal responsibility if Hermann Zapf is turning over in his grave.
\documentclass{article}
\usepackage{stackengine}
\usepackage{graphicx,xcolor}
\def\fauxat{\raisebox{-.35ex}{\stackinset{c}{+.05ex}{c}{-.13ex}{\scalebox{.82}{%
\stackunder[.1pt]{\itshape a}{\textcolor{white}{%
\kern.7ex\rule{1ex}{.2ex}}}}}{\textsf{\textit{O}}}}}
\def\fauxAt{\raisebox{-.38ex}{\stackinset{c}{+.09ex}{c}{-.07ex}{\scalebox{.73}{%
\stackunder[.0pt]{\itshape A}{\textcolor{white}{%
\kern.7ex\rule{1ex}{.2ex}}}}}{\scalebox{1.2}{\textsf{\textit{O}}}}}}
\parindent 0pt
\begin{document}
mailto:name\fauxat domain.tld
mailto:NAME\fauxAt DOMAIN.TLD
\end{document}

If one finds the surrounding "O" too thick for the symbol, one can remove the occurrence of \textsf
to get the following. I think it actually looks nicer.

;-)