
</tt></td></tr>
</table>
</blockquote>

<p class=parameters>
For a simple message, all that is needed is a set of <tt>headers</tt>
and the <tt>body</tt>. The message <tt>body</tt> can be given as a string
or as a <em>simple</em> 
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> 
source. For multipart messages, the body is a table that
recursively defines each part as an independent message, plus an optional
<tt>preamble</tt> and <tt>epilogue</tt>.
</p>

<p class=return> 
The function re