<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:openaccess">
   <soapenv:Header>
      <urn:ResponseLimitationHeader>
         <!--Optional:-->
         <urn:range>
            <urn:from>1</urn:from>
            <urn:to>500</urn:to>
         </urn:range>
         <!--Optional:-->
         <urn:resultSize>500</urn:resultSize>
      </urn:ResponseLimitationHeader>
      <urn:SessionToken>
         <urn:userLoginName>API</urn:userLoginName>
         <urn:sessionKey>32183292503045424638101483539644037108615890855816568805459049649506625396455985</urn:sessionKey>
      </urn:SessionToken>
      <urn:AsynchronousResponseHeader>
         <urn:asynchronousResponse>1</urn:asynchronousResponse>
         <!--Optional:-->
         <urn:responseToken>1</urn:responseToken>
      </urn:AsynchronousResponseHeader>
   </soapenv:Header>
   <soapenv:Body>
      <urn:RetrieveMessagesUnreadOnly>
         <Boolean>1</Boolean>
      </urn:RetrieveMessagesUnreadOnly>
   </soapenv:Body>
</soapenv:Envelope>