邮件发送 利用SMTP

 System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient();
        client.Host = "smtp.qq.com";
        client.UseDefaultCredentials = false;
        client.Credentials = new System.Net.NetworkCredential("邮箱用户名", "邮箱密码");
        client.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network;
        System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage("发件人的邮箱", "收件人的邮箱");
        message.Subject = "关于XX的处罚决定";
        message.Body = "<center>关于XX的处罚决定</center><br/>关于XX的处罚决定关于XX的处罚决定关于XX的处罚决定关于XX的处罚决定";
        message.BodyEncoding = Encoding.UTF8;
        message.IsBodyHtml = true;
        System.Net.Mail.Attachment m;//附件
        if (this.FileUpload1.HasFile)
        {
            m = new System.Net.Mail.Attachment(this.FileUpload1.PostedFile.FileName);
            message.Attachments.Add(m);
        }
        client.Send(message);