In EWS, you can create a draft like this:
<tns:CreateItem MessageDisposition="SaveOnly">
<tns:Items>
<t:Message>
<t:ItemClass>IPM.Note</t:ItemClass>
<t:Subject>subject</t:Subject>
<t:Body BodyType="HTML">body</t:Body>
<t:IsRead>false</t:IsRead>
</t:Message>
</tns:Items>
</tns:CreateItem>
What do I need to add to create a regular message instead of a draft, as the code above does (using SOAP messages, not the Managed API)?
Setting the extended MessageFlags property did the trick! Has to be done at creation.
<tns:CreateItem MessageDisposition="SaveOnly">
<tns:Items>
<t:Message>
<t:ItemClass>IPM.Note</t:ItemClass>
<t:Subject>subject</t:Subject>
<t:Body BodyType="HTML">body</t:Body>
<t:IsRead>false</t:IsRead>
<t:ExtendedProperty>
<t:ExtendedFieldURI PropertyTag="3591" PropertyType="Integer" />
<t:Value>1</t:Value>
</t:ExtendedProperty>
</t:Message>
</tns:Items>
</tns:CreateItem>
来源:https://stackoverflow.com/questions/31147045/soap-message-to-ews-to-create-mail-as-regular-mail-not-draft