dHeader&#8203;(java.lang.String&nbsp;header_name,
               java.lang.String&nbsp;header_value)
        throws <a href="MessagingException.html" title="class in jakarta.mail">MessagingException</a></pre>
<div class="block">Add this value to the existing values for this header_name.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>header_name</code> - the name of this header</dd>
<dd><code>header_value</code> - the value for this header</dd>
<dt><span class="throwsLabel">Throws: