MailMessage message = new MailMessage(fromEmail, toEmail);
message.Subject = “xxx”;
message.Body = “xxx”;
message.IsBodyHtml = true; 
SmtpClient client = new SmtpClient();
//VS2005下必须设置Credentials,而vs2008下不须设置
NetworkCredential myCredentials = new NetworkCredential(fromEmail,password, "");
client.Credentials = myCredentials;
client.Send(message);