Sending Meeting invite with mail attachment

Question

I have created a MailMessage which is really a meeting request but problem is when it shows up in my Outlook I can accept/decline like with any other meeting request. This is great. However, now I am trying to add attachments to the MailMessage when I do this, it successfully adds the attachment however when the email is received in Outlook it is no longer a meeting request I can accept/decline, instead it's just an email with the meeting information inside of it and the attachment attached. How do I programmatically attach the attachment while at the same time keeping the meeting request functionality?