Hello.
Here[
^] is aMS Support article showing how to send email via outlooik. The major difference I can see between your code and MS support code is, how the message gets created. May be following code wrok's correctly for you.
Outlook.Application oApp = new Outlook.Application();
Outlook.MailItem oMsg = (Outlook.MailItem)oApp.CreateItem(Outlook.OlItemType.olMailItem);
Outlook.Recipient oRecip = (Outlook.Recipient) oMsg.Recipients.Add(receiver[0]);
oRecip.Resolve();
oMsg.Subject = "test";
oMsg.Body = "This is a stupid dummy text.\nIt is here to test if sending stupid emails even with a dummy text is not possible correctly!\n\nIn Love\nyour cookie!";
oMsg.Save();
oMsg.Send();
Regards,