Xpath
/control/message/preserve-link-category
Example request
<control xmlns="http://webservices.ecircle-ag.com/ecm"
request-id="Unique-String" group-id="1200735989">
<message message-id="new" clone-from-id="1202515907">
<send-date>
<immediately/>
</send-date>
<preserve-link-category>true</preserve-link-category>
</message>
</control>