LinkedResource Class

protected void submit_Button(object sender, EventArgs e)
    {
       
//Creates the mail message

MailMessage mail = new MailMessage();
       
       //This is the string of the message body
        string nImage = "This is a test of the system. <img src=cid:myPicture>";

//Creates the Alternate view for html
        AlternateView hView= AlternateView.CreateAlternateViewFromString(nImage,null,"text/html");

        LinkedResource myPicture = new LinkedResource("C:\\Users\\user(change this to you)\\Documents\\Visual Studio 2010\\WebSites\\TestSite\\images\\thumbnail.jpg");
        myPicture.ContentId = "myPicture";
        nView.LinkedResources.Add(myPicture);

       
   //Normal mail stuff
        mail.To.Add("email@you.com");

        mail.From = new MailAddress("email@mail.com");
      
        mail.AlternateViews.Add(nView);
        SmtpClient client = new SmtpClient();
        client.Send(mail);
     

    }

//To embed images, we need to use the prefix 'cid' in the img src value
//the cid value will map to the Content-Id of a Linked resource.
//thus <img src='cid:myPicture'> will map to a LinkedResource with a ContentId of 'myPicture'
Alternateview view = Alternateview.CreateAlternateviewFromString("Here is an embedded image.<img src=cid:myPicture>", null, "text/html");
//Create the LinkedResource
LinkedResource myPicture = new LinkedResource( "c:\\temp\\Picture.gif" );
logo.ContentId = "myPicture";
//Add the LinkedResource to the iew
htmlview.LinkedResources.Add(myPicture);
mail.Alternateviews.Add(view);