AlternateView plainView = AlternateView.CreateAlternateViewFromString(
                        Regex.Replace(EmailBody, @"<(.|\n)*?>", string.Empty), null, "text/plain");
AlternateView htmlView = AlternateView.CreateAlternateViewFromString(EmailBody, null, "text/html");
MyMsg.AlternateViews.Add(plainView);
MyMsg.AlternateViews.Add(htmlView);

using System.Net.Mail;
using System.Text.RegularExpressions;