c# 发送邮件

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;using System.Net.Mail;namespace WindowsFormsApplication1{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void button1_Click(object sender, EventArgs e)        {            System.Net.Mail.SmtpClient client = new SmtpClient("smtp.qq.com");            client.UseDefaultCredentials = false;            client.Credentials = new System.Net.NetworkCredential("[e-mail]", "yyyyy");            client.DeliveryMethod = SmtpDeliveryMethod.Network;            MailAddress addressFrom = new MailAddress("[e-mail]", "xxxx");            MailAddress addressTo = new MailAddress("[e-mail]", "test");            System.Net.Mail.MailMessage message = new MailMessage(addressFrom, addressTo);            message.Sender = new MailAddress("[e-mail]");            message.BodyEncoding = System.Text.Encoding.UTF8;            message.IsBodyHtml = true;            message.Subject = "test";            client.Send(message);         }           }}