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("xxxx@qq.com", "yyyyy");
            client.DeliveryMethod = SmtpDeliveryMethod.Network;

            MailAddress addressFrom = new MailAddress("xxxx@qq.com", "xxxx");
            MailAddress addressTo = new MailAddress("test@gmail.com", "test");

            System.Net.Mail.MailMessage message = new MailMessage(addressFrom, addressTo);
            message.Sender = new MailAddress("xxxx@qq.com");
            message.BodyEncoding = System.Text.Encoding.UTF8;
            message.IsBodyHtml = true;
            message.Subject = "test";

            client.Send(message); 

        }
       
    }
}