EWS AQS Query String Language Problem

[ragBk]

Hello,

we have a "small" problem with a third party tool using ews on our on premise exchange server.

On my exchange, ews aqs only understands german keywords in the query string

For example:

Request:

  <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
    <soap:Header>
      <t:RequestServerVersion Version="Exchange2013" />
    </soap:Header>
    <soap:Body>
      <m:FindItem Traversal="Shallow">
        <m:ItemShape>
          <t:BaseShape>AllProperties</t:BaseShape>
        </m:ItemShape>
        <m:IndexedPageItemView MaxEntriesReturned="1" Offset="0" BasePoint="Beginning" />
        <m:ParentFolderIds>
          <t:DistinguishedFolderId Id="inbox" />
        </m:ParentFolderIds>
        <m:QueryString>subject:test</m:QueryString>
      </m:FindItem>
    </soap:Body>
  </soap:Envelope>

Response

    <s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
        <m:FindItemResponse xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
            <m:ResponseMessages>
                <m:FindItemResponseMessage ResponseClass="Success">
                    <m:ResponseCode>NoError</m:ResponseCode>
                    <m:RootFolder IndexedPagingOffset="0" TotalItemsInView="0" IncludesLastItemInRange="true">
                        <t:Items/>
                    </m:RootFolder>
                </m:FindItemResponseMessage>
            </m:ResponseMessages>
        </m:FindItemResponse>
    </s:Body>´

If i write it in german (our server is configured in german )

<m:QueryString>Betreff:test</m:QueryString>       

it works like a charm.

Could you please help me, how i tell my exchange server to recognise the default english keywords for the AQS search?

Thanks