ТЕМА:

msg = new MailMessage("xxxx@gmail.com",
                "yyyy@gmail.com", "Message from PSSP System",
                "This email sent by the PSSP system<br />" +
                "<b>this is bold text!</b>");

msg.IsBodyHtml = true;

<table>
    <tr>
        <td>
            Dealer Company Name
        </td>
        <td>
            :
        </td>
        <td>
            #DealerCompanyName#
        </td>
    </tr>
</table>

string Body = System.IO.File.ReadAllText(HttpContext.Current.Server.MapPath("EmailTemplates/Customer.htm"));

Body = Body.Replace("#DealerCompanyName#", _lstGetDealerRoleAndContactInfoByCompanyIDResult[0].CompanyName);

public static void SendEmail(string Body)
        {
            MailMessage message = new MailMessage();
            message.From = new MailAddress(Session["Email"].Tostring());
            message.To.Add(ConfigurationSettings.AppSettings["RequesEmail"].ToString());
            message.Subject = "Request from " + SessionFactory.CurrentCompany.CompanyName + " to add a new supplier";
            message.IsBodyHtml = true;
            message.Body = Body;

            SmtpClient smtpClient = new SmtpClient();
            smtpClient.UseDefaultCredentials = true;

            smtpClient.Host = ConfigurationSettings.AppSettings["SMTP"].ToString();
            smtpClient.Port = Convert.ToInt32(ConfigurationSettings.AppSettings["PORT"].ToString());
            smtpClient.EnableSsl = true;
            smtpClient.Credentials = new System.Net.NetworkCredential(ConfigurationSettings.AppSettings["USERNAME"].ToString(), ConfigurationSettings.AppSettings["PASSWORD"].ToString());
            smtpClient.Send(message);
        }

msg.BodyFormat = MailFormat.Html;

msg.Body = "<em>It great to use HTML in mail!!</em>"