发送邮件。。

private void button2_Click(object sender, EventArgs e)
        {

            //创建邮件服务器对象
            SmtpClient smtp = new SmtpClient("smtp.sina.cn");

            //创建发件人对象
            MailAddress from = new MailAddress("18560812711@sina.cn");

            //创建收件人对象
            MailAddress to = new MailAddress(textBox1.Text);

            //创建邮件对象，构造函数中传入发件人和收件人
            MailMessage mess = new MailMessage(from, to);

            //设置邮件的标题
            mess.Subject = "【阿狸粑粑的验证码邮件】";

            string aaa = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";

            Random r = new Random();

            for (int i = 0; i < 16; i++)
            {
                yzm += aaa.Substring(r.Next(0, aaa.Length), 1);
            }

            //设置邮件的内容
            mess.Body = "您的验证码为：" + yzm + "，请在20分钟内验证，系统邮件请勿回复！";

            //创建互联网安全证书
            NetworkCredential cred = new NetworkCredential("18560812711@sina.cn", "hq1234561");

            //将证书绑定到服务器对象以便服务器验证
            smtp.Credentials = cred;

            //通过服务器对象将邮件发送出去
            smtp.Send(mess);
            MessageBox.Show("邮件发送成功，请尽快验证！");

            button2.Enabled = false;
            timer1.Enabled = true;
            time = 10;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (textBox2.Text == yzm)
            {
                MessageBox.Show("验证成功！");
            }
            else
            {
                MessageBox.Show("失败！！！！");
            }
        }