I was wondering if anyone using the API might have figured out an answer to this. I wish to use the API to send an email message that has an attached file and the API documentation is sadly lacking on how to accomplish this. Using Fiddler, I see that WebMail uses api/upload but there is no mention of this method at all in the documentation. There are the methods UploadFile and AddAttachment but the documentation does not explain how to use these methods. The documentation for UploadFile does not list or explain what the inputs should be and the documentation for AddAttachment lists attachguid and contentid as inputs but offers no explanation of what these parameters represent or how to obtain values for them. If anyone has any information, I would appreciate it.