C#发送邮件（Gmail到qq邮箱和163邮箱）

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

using System.Net.Mail;
using System.Net;

namespace SendEmail
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            #region 邮件信息
            string emailFromAddress = "[e-mail]";
            string emailPassword = "YourPassword";
            string emailToAddress1 = "[e-mail]";
            string emailToAddress2 = "[e-mail]";
            string emailSubject = "C#发送Email";
            string emailBody = "this is a test email from gmail!" + System.DateTime.Now;
            #endregion
            try
            {
                MailMessage myMail = new MailMessage();
                myMail.From = new MailAddress(emailFromAddress);
                myMail.To.Add(new MailAddress(emailToAddress1));
                myMail.To.Add(new MailAddress(emailToAddress2));
                myMail.Subject = emailSubject;
                myMail.SubjectEncoding = Encoding.UTF8;

                myMail.Body = emailBody;
                myMail.BodyEncoding = Encoding.UTF8;
                myMail.IsBodyHtml = true;

                SmtpClient smtp = new SmtpClient();
                smtp.Host = "smtp.gmail.com";
                smtp.Port = 587;                    //Gmail的smtp端口
                smtp.Credentials = new NetworkCredential(emailFromAddress, emailPassword);
                smtp.EnableSsl = true;              //Gmail要求SSL连接
                smtp.DeliveryMethod = SmtpDeliveryMethod.Network; //Gmail的发送方式是通过网络的方式，需要指定

                smtp.Send(myMail);
                MessageBox.Show("发送成功");
            }
            catch (Exception err) 
            {
                MessageBox.Show("发送失败！原因是"+err.Message+err.Source);
            }
        }
    }
}