how to send multi part MIME email (text and HTML)

//create the mail message
var mail = new MailMessage();
//set the addresses
mail.From = new MailAddress("[email protected]");
mail.To.Add("[email protected]");
//set the content
mail.Subject = "This is an email";
//first we create the Plain Text part
var plainView = AlternateView.CreateAlternateViewFromString("This is my plain text content, viewable by those clients that don't support html", null, "text/plain");
//then we create the Html part
var htmlView = AlternateView.CreateAlternateViewFromString("this is bold text, and viewable by those mail clients that support html", null, "text/html");
mail.AlternateViews.Add(plainView);
mail.AlternateViews.Add(htmlView);
//send the message
var smtp = new SmtpClient("127.0.0.1");
//specify the mail server address
smtp.Send(mail);