问如何使用Office365预览API添加自定义邮件头

EN

//Create the new Message with the Office365 API and save it to the Drafts folder
var client = await EnsureClientCreated();
var o365Message = new Microsoft.Office365.Exchange.Message();            
string subject = "Test subject";
o365Message.Subject = subject;
o365Message.Body = new ItemBody() { Content = "Test", ContentType = BodyType.Text };
messageModel.Subject = subject;
var recip = new Recipient();
recip.Address = "test@test.com";
o365Message.ToRecipients.Add(recip);
await client.Me.Drafts.Messages.AddMessageAsync(o365Message, false);