1.添加引用

　　using System.Net.Mail;

2.發送郵件實現代碼

        private void btnsend_Click(object sender, EventArgs e)
        {
            try
            {
                var senduser = ConfigurationManager.AppSettings["senduser"];// "[email protected]";
                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";//主題
                message.Body = sendmsg;//內容
                message.Attachments.Add(new Attachment("test.txt"));//附件

                SmtpClient client = new SmtpClient("smtp.qq.com", 25);//基於qq郵件發送
                client.Credentials = new
 
 NetworkCredential(senduser, sendpwd);
                client.EnableSsl = true;
                client.Send(message);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

c#基於System.Net.Mail實現發送郵件功能