Delay sending an email via EWS leaves mail in sent-items without actually sending it

Question

I'm trying to delay-send an email through EWS (Exchange 2019) from a Word VBA module. This works fine, as long as I send immediately. As soon as I add the element for delayed send

<t:ExtendedProperty>
  <t:ExtendedFieldURI PropertyTag="16367" PropertyType="SystemTime" />
  <t:Value>2022-01-01T00:00:00.000</t:Value>
</t:ExtendedProperty>

The mail goes into sent items immediately and does not get delivered. This is the entire code - the XML is below for better readability:

Private Sub SendEMail()
  Dim sReq As String
  Dim xmlMethod As String
  Dim XMLreq As New MSXML2.XMLHTTP60
  Dim EWSEndPoint As String
  
  Dim t As String
  t = "2022-01-01T00:00:00.000"
  
  EWSEndPoint = "https://myexchange/EWS/Exchange.asmx"
  sReq = "<?xml version=""1.0"" encoding=""UTF-8""?>" & vbCrLf & _
          "<soap:Envelope xmlns:soap=""http://schemas.xmlsoap.org/soap/envelope/"" xmlns:t=""http://schemas.microsoft.com/exchange/services/2006/types"">" & vbCrLf & _
            "<soap:Header>" & vbCrLf & "<t:RequestServerVersion Version=""Exchange2016""/>" & vbCrLf & "</soap:Header>" & vbCrLf & _
            "<soap:Body>" & vbCrLf & _
              "<CreateItem MessageDisposition=""SendAndSaveCopy"" xmlns=""http://schemas.microsoft.com/exchange/services/2006/messages"">" & vbCrLf & _
                "<SavedItemFolderId>" & vbCrLf & _
                  "<t:DistinguishedFolderId Id=""sentitems"" />" & vbCrLf & _
                "</SavedItemFolderId>" & vbCrLf & _
                "<Items>" & vbCrLf & _
                  "<t:Message>" & vbCrLf & _
                    "<t:ItemClass>IPM.Note</t:ItemClass>" & vbCrLf & _
                    "<t:Subject>" & "123 " & Now() & " für " & t & "</t:Subject>" & vbCrLf & _
                    "<t:Body BodyType=""Text"">" & "body" & "</t:Body>" & vbCrLf & _
                    "<t:ExtendedProperty>" & vbCrLf & _
                      "<t:ExtendedFieldURI PropertyTag=""16367"" PropertyType=""SystemTime"" />" & vbCrLf & _
                      "<t:Value>" & t & "</t:Value>" & vbCrLf & _
                    "</t:ExtendedProperty>" & vbCrLf & _
                    "<t:ToRecipients>" & vbCrLf & _
                      "<t:Mailbox>" & vbCrLf & "<t:EmailAddress>" & "myemail" & "</t:EmailAddress>" & vbCrLf & "</t:Mailbox>" & vbCrLf & _
                    "</t:ToRecipients>" & vbCrLf & _
                  "</t:Message>" & vbCrLf & _
                "</Items>" & vbCrLf & _
              "</CreateItem>" & vbCrLf & _
            "</soap:Body>" & vbCrLf & _
          "</soap:Envelope>" & vbCrLf

  xmlMethod = "POST"
  XMLreq.Open xmlMethod, EWSEndPoint, False, "myusername", "mypassword"
  XMLreq.setRequestHeader "Content-Type", "text/xml; charset=""UTF-8"""
  XMLreq.Send sReq

  If XMLreq.Status = 200 Then
                    ' Message Sent okay
                    MsgBox ("ok")
  Else
                    ' Something went Wrong
                    MsgBox ("error")
  End If
End Sub

And here's the XML:

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
<soap:Header>
<t:RequestServerVersion Version="Exchange2016"/>
</soap:Header>
<soap:Body>
<CreateItem MessageDisposition="SendAndSaveCopy" xmlns="http://schemas.microsoft.com/exchange/services/2006/messages">
<SavedItemFolderId>
<t:DistinguishedFolderId Id="sentitems" />
</SavedItemFolderId>
<Items>
<t:Message>
<t:ItemClass>IPM.Note</t:ItemClass>
<t:Subject>123 31.03.2021 13:35:19 für 2022-01-01T00:00:00.000</t:Subject>
<t:Body BodyType="Text">body</t:Body>
<t:ExtendedProperty>
<t:ExtendedFieldURI PropertyTag="16367" PropertyType="SystemTime" />
<t:Value>2022-01-01T00:00:00.000</t:Value>
</t:ExtendedProperty>
<t:ToRecipients>
<t:Mailbox>
<t:EmailAddress>myemail</t:EmailAddress>
</t:Mailbox>
</t:ToRecipients>
</t:Message>
</Items>
</CreateItem>
</soap:Body>
</soap:Envelope>

I am in Europe here, so 24-hour-timeformat. To avoid any hazzle with time and date formatting, I have taken a simple day in the example, but that did not make any difference. I've tried past and future dates, no change: The mail goes to sent items immediately and does not send. (The xmlreq.send-lines always closes without error.) As soon as I remove the four extendedproperty-lines, it sends without problems.

What is it that I'm overlooking?

Answer 1

Remove the SavedFolderId it's optional anyway but when i test your XML with it I see the same problem so

<?xml version="1.0" encoding="UTF-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
<soap:Header>
<t:RequestServerVersion Version="Exchange2016"/>
</soap:Header>
<soap:Body>
<CreateItem MessageDisposition="SendAndSaveCopy" xmlns="http://schemas.microsoft.com/exchange/services/2006/messages">
<Items>
<t:Message>
<t:ItemClass>IPM.Note</t:ItemClass>
<t:Subject>123 31.03.2021 13:35:19 für 2022-01-01T00:00:00.000</t:Subject>
<t:Body BodyType="Text">body</t:Body>
<t:ExtendedProperty>
<t:ExtendedFieldURI PropertyTag="16367" PropertyType="SystemTime" />
<t:Value>2021-03-31T23:06:00.000</t:Value>
</t:ExtendedProperty>
<t:ToRecipients>
<t:Mailbox>
<t:EmailAddress>glenscales@yahoo.com</t:EmailAddress>
</t:Mailbox>
</t:ToRecipients>
</t:Message>
</Items>
</CreateItem>
</soap:Body>
</soap:Envelope>

works okay for me, It does save the message temporary to the drafts folder (instead of the outbox) but once sent the message does end up in the SentItems Folder.