C# 发送邮件 附件名称为空

// 1.创建邮件
MailMessage mailMsg = new MailMessage();
mailMsg.To.Add(new MailAddress("test@test.com"));

// 2.设置邮件标题、正文等信息
mailMsg.HeadersEncoding = Encoding.GetEncoding("gb2312");
mailMsg.SubjectEncoding = Encoding.GetEncoding("gb2312");
mailMsg.BodyEncoding = Encoding.GetEncoding("gb2312"); // 邮件内容编码
mailMsg.Subject = emailTitleStr; // 邮件标题
mailMsg.Body = emailBodyStr;
mailMsg.IsBodyHtml = true; // 邮件内容是否支持html
mailMsg.Priority = MailPriority.High;
// 附件：在 .net 4.0中，附件名称含有特殊名称时，接收方将收到名字为空的附件
mailMsg.Attachments.Add(new Attachment("D:\资料(2016).txt"));

// 3.创建SMTP发送
SmtpClient smtp = new SmtpClient(emailSMTP, emailPort);
smtp.Credentials = new NetworkCredential(emailName.Address, emailPwd);
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Send(mailMsg);