Asp.net/C# 在多个电子邮件下载时附加标头错误

问：

我有一个 asp.net/c# 应用程序，它有一个功能，用户可以触发它是什么，然后下载一封电子邮件。如果有一封电子邮件被触发/下载，那完全可以正常工作。但是，如果有多封电子邮件，我会收到“发送 HTTP 标头后服务器无法追加标头”错误。我搞砸了，做了一些谷歌 fu，但似乎没有任何效果。

生成第一封电子邮件后，它会在“Response.AddHeaders”行上出错。

public void EmailDownload(string toAddress, string ccAddress, string subject, string body, string downloadName)
    {
        var assembly = typeof(SmtpClient).Assembly;
        var mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");

        using (MemoryStream stream = new MemoryStream())
        {

            MailMessage message = new MailMessage();
            message.Body = body;
            //message.To.Add(new MailAddress(toAddress));
            message.To.Add(new MailAddress(emailAddress);

            if (!string.IsNullOrEmpty(ccAddress))
            {
                message.CC.Add(new MailAddress(ccAddress));
            }
            //message.From = new MailAddress("[email protected]");
            message.From = new MailAddress(emailAddress);
            message.Subject = subject;
            message.Headers.Add("X-Unsent", "1");
            message.IsBodyHtml = true;

            // Get reflection info for MailWriter contructor
            var mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);

            // Construct MailWriter object with our FileStream
            var mailWriter = mailWriterContructor.Invoke(new object[] { stream });

            // Get reflection info for Send() method on MailMessage
            var sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);

            // Call method passing in MailWriter
            sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true, true }, null);

            // Finally get reflection info for Close() method on our MailWriter
            var closeMethod = mailWriter.GetType().GetMethod("Close", BindingFlags.Instance | BindingFlags.NonPublic);

            // Call close method
            closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);

            byte[] data = stream.ToArray();
            stream.Close();
            Response.Clear();
            Response.ContentType = "application/force-download";
            Response.AddHeader("content-disposition", "attachment;    filename=" + downloadName + ".eml");
            Response.BinaryWrite(data);
            //Response.End();
            Response.Flush();
            Response.SuppressContent = true;
            HttpContext.Current.ApplicationInstance.CompleteRequest();
        }
    }