配置文件中加入

MailMessage msg = new MailMessage();      msg.From = new MailAddress("475504513@qq.com");      msg.To.Add(new MailAddress("475504513@qq.com"));      msg.Subject = "测试Subject";      msg.Body = "测试Body";      msg.IsBodyHtml = false;      SmtpClient smtp = new SmtpClient();      smtp.Send(msg);

代码中配置信息

public static string CreateTimeoutTestMessage(string server)        {            string Success = "发送成功";            try            {                string _to = "1035092449@qq.com";                string _from = "young-20@163.com";                string _subject = "Using the new SMTP client.";                string _body = @"Using this new feature, you can send an e-mail message from an application very easily.";                MailMessage message = new MailMessage();                message.From = new MailAddress(_from);                //可以利用MailMessage.To.Add方法增加要发送的邮件地址                message .To .Add (new MailAddress ("652105072@qq.com"));                message.To.Add(new MailAddress(_to));                message.Subject = _subject;                message.Body = _body;                //添加附件                Attachment a = new Attachment(@"C:/Users/Administrator/Desktop/smtpclient.rar");                message.Attachments.Add(a);                //设置邮箱的地址或IP                SmtpClient client = new SmtpClient(server);                //设置邮箱端口，pop3端口:110, smtp端口是:25                 client.Port = 25;                                //设置超时时间                client.Timeout = 9999;                                //要输入邮箱用户名与密码                                client.Credentials = new NetworkCredential("young-20@163.com", "******");                client.Send(message);            }            catch (Exception ex)            {                Success = ex.ToString();            }            return Success;        }

调用方法CreateTimeoutTestMessage("smtp.qq.com"),邮箱需要开启SMTP功能，QQ在设置，账户下启用