paper e551 has an author that is a group rather than a human.
the group name is enclosed in a <collab> element in the XML rather than a <name> element.
the group name is not included in author list when the paper is emailed - it looks like the email script only pulls <name> elements from each <contrib>
here's the XML for an author and the group from this paper:
<contrib contrib-type="author" xlink:type="simple">
<name name-style="western"><surname>McArthur</surname><given-names>Justin C.</given-names></name>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple">
<collab xlink:type="simple">for the Neurologic AIDS Research Consortium and the AIDS Clinical Trials Group</collab>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<xref ref-type="aff" rid="aff4"><sup>4</sup></xref>
<xref ref-type="aff" rid="aff5"><sup>5</sup></xref>
</contrib>
