block">This method sets the given Multipart object as this message's
 content.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>mp</code> - The multipart object that is the Message's content</dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="IllegalWriteException.html" title="class in jakarta.mail">IllegalWriteException</a></code> - if the underlying 
                        implementation  does not support modification of 
                        existing val