\section{Rule number 1: signatures}
\begin{frame}{Good or bad?}
    \lstinputlisting{assets/bad.sig}
\end{frame}
\begin{frame}{Good or bad?}
    \lstinputlisting{assets/good.sig}
\end{frame}
\begin{frame}{Why?}
    RFC 1855~\cite{rfc1855} clearly states that:\vspace{1em}

    \begin{quote}
      If you include a signature keep it short.  Rule of thumb
      is no longer than 4 lines. Remember that many people pay for
      connectivity by the minute, and the longer your message is,
      the more they pay.
    \end{quote}
\end{frame}
\begin{frame}{How to (Thunderbird)}
    \centering
    \includegraphics[scale=0.35]{target/slides-thunderbird-sig.jpg}
\end{frame}
\begin{frame}{How to (neomutt)}
    \centering
    \lstinputlisting[language=sh]{assets/muttrc-sig.conf}
\end{frame}