c#基于System.Net.Mail实现发送邮件功能

1.添加引用

　　using System.Net.Mail;

2.发送邮件实现代码

        private void btnsend_Click(object sender, EventArgs e)
        {
            try
            {
                var senduser = ConfigurationManager.AppSettings["senduser"];// "test@qq.com";
                var sendpwd = ConfigurationManager.AppSettings["sendpwd"];// "test";

                var receiver = this.txtreceiver.Text;
                var sendmsg = this.txtsendmsg.Text;

                var message = new MailMessage();
                var fromddress = new MailAddress(senduser);
                message.From = fromddress;

                message.To.Add(receiver);//接收方
                message.CC.Add(receiver);//抄送方
                message.Subject = "test";//主题
                message.Body = sendmsg;//内容
                message.Attachments.Add(new Attachment("test.txt"));//附件

                SmtpClient client = new SmtpClient("smtp.qq.com", 25);//基于qq邮件发送
                client.Credentials = new NetworkCredential(senduser, sendpwd);
                client.EnableSsl = true;
                client.Send(message);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

--qq邮件要求：
//验证发件人身份(发件人的邮箱，邮箱里的生成授权码);
client.Credentials = new NetworkCredential("123456@qq.com", "fnsedjxib");