diff --git a/Doc/texinputs/python.sty b/Doc/texinputs/python.sty
index 498fc3b..6b892cb 100644
--- a/Doc/texinputs/python.sty
+++ b/Doc/texinputs/python.sty
@@ -833,6 +833,7 @@
 \newcommand{\ctype}[1]{\texttt{#1}}     % C struct or typedef name
 \newcommand{\cdata}[1]{\texttt{#1}}     % C variable, typically global
 
+\newcommand{\mailheader}[1]{\texttt{#1}}
 \newcommand{\mimetype}[1]{{\small\textsf{#1}}}
 % The \! is a "negative thin space" in math mode.
 \newcommand{\regexp}[1]{%