Request
-----------------
POST https://outlook.office365.com/EWS/Exchange.asmx HTTP/1.1
Authorization: Bearer xxxxxx (omitted)
Content-Type: text/xml; charset=utf-8
Host: outlook.office365.com
Content-Length: 1262

<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
  <soap:Header>
    <t:RequestServerVersion Version="Exchange2013" />
  </soap:Header>
  <soap:Body>
    <UpdateItem MessageDisposition="SaveOnly" ConflictResolution="AutoResolve"
    xmlns="http://schemas.microsoft.com/exchange/services/2006/messages">
      <ItemChanges>
        <t:ItemChange>
          <t:ItemId Id = "AAMkAGI3NDEzZjRhLWU3ZjktNGViNy04MTI1LWFhOWRiZDRlY2QwNABGAAAAAADBaXFYA4KPQqsQBpmZF2+2BwAa6KJzOcvaRKcc5UfLbF5tAAAA4fK1AAACk4HLLuxASqDPNieBkIv8AANIKlICAAA=" ChangeKey="CQAAABYAAAACk4HLLuxASqDPNieBkIv8AANIb3mG"/>
          <t:Updates>

            <t:SetItemField>
              <t:FieldURI FieldURI = "item:Categories" />
              <t:Message>
                <t:Categories>
                  <t:String>Workout</t:String>
                </t:Categories>
              </t:Message>
            </t:SetItemField>
          </t:Updates>
        </t:ItemChange>
      </ItemChanges>
    </UpdateItem>
  </soap:Body>
</soap:Envelope>



Response
------------
HTTP/1.1 500 Internal Server Error
Cache-Control: private
Content-Length: 673
Content-Type: text/xml; charset=utf-8
Server: Microsoft-IIS/8.0
request-id: db9b1db2-ed0d-40ed-ab1d-74d2182e145d
X-CalculatedBETarget: AM3PR06MB1202.eurprd06.prod.outlook.com
X-BackEndHttpStatus: 500
Set-Cookie: exchangecookie=5f0e77b2ba2647e2a26565e8e4adad39; expires=Fri, 08-Sep-2017 15:23:08 GMT; path=/; HttpOnly
x-ms-diagnostics: 2000008;reason="The web method in the request is not allowed with this token.";error_category="invalid_grant"
X-AspNet-Version: 4.0.30319
X-DiagInfo: AM3PR06MB1202
X-BEServer: AM3PR06MB1202
X-Powered-By: ASP.NET
X-FEServer: AM3PR01CA024
Date: Thu, 08 Sep 2016 15:23:07 GMT

<?xml version="1.0" encoding="utf-8"?><s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"><s:Body><s:Fault><faultcode xmlns:a="http://schemas.microsoft.com/exchange/services/2006/types">a:ErrorAccessDenied</faultcode><faultstring xml:lang="en-US">The requested web method is unavailable to this caller or application.</faultstring><detail><e:ResponseCode xmlns:e="http://schemas.microsoft.com/exchange/services/2006/errors">ErrorAccessDenied</e:ResponseCode><e:Message xmlns:e="http://schemas.microsoft.com/exchange/services/2006/errors">The requested web method is unavailable to this caller or application.</e:Message></detail></s:Fault></s:Body></s:Envelope>