I was recently looking for a way to add an email to a user's draft folder with attachements. Exchange web services was the ticket. See the screen shot and code snippet attached.
The trick is to add to a user's outlook draft folder you need a user id with higher level rights and allow impersonation must be turned on in Exchange.
public partial class ActiveXTest : System.Web.UI.Page
ExchangeService service = new ExchangeService(ExchangeVersion.Exchange2010);
protected void Page_Load(object sender, EventArgs e)
service.Credentials = new WebCredentials("youremail", "yourpassword");
service.Url = new Uri("https://client.yourexchangeserver.com/ews/exchange.asmx");
protected void BtnCreateMsg_Click(object sender, EventArgs e)
EmailMessage message = new EmailMessage(service);
message.Subject = TxtSubject.Text;
string MSG = TxtBody.Text;
MSG = MSG.Replace("\n", "
message.Body = MSG;
message.Attachments.AddFileAttachment(@"C:\temp\TEST Word Doc.docx");
LblMsg.Text = "Email created, please check your draft folder";