//SmtpClient client = new SmtpClient("smtp.qq.com");

             //client.EnableSsl = true;

             //client.UseDefaultCredentials = false;

             //client.Credentials = new System.Net.NetworkCredential(email, key);

             //client.Send("from email", "to email", "Title", "Content");

             SmtpClient client = new SmtpClient("smtp.qq.com");

             client.EnableSsl = true;

             client.UseDefaultCredentials = false;

             client.Credentials = new System.Net.NetworkCredential("email", "key");

             MailMessage m = new MailMessage();

             m.From = new MailAddress("from email", "name");

             m.To.Add(new MailAddress("to email", "name"));

             m.CC.Add(new MailAddress("cc email", "name"));

             m.Subject = "This is Title";

             m.Body = " long Message";

             m.IsBodyHtml = true;

             m.Priority = MailPriority.High;

             Attachment att = new Attachment("ad.zip", MediaTypeNames.Application.Zip); //项目路径下文件

             m.Attachments.Add(att);

             client.Send(m);