c# - 使用 .net 中的 Pop3.dll 从 MailBox 下载电子邮件附件

Question

我正在使用 vs 2010 开发使用 c# 的 winform 应用程序。

对于从邮箱下载电子邮件附件，我使用了 pop3.dll

当我在直接连接到 Internet 的机器上使用它时，我的代码下载附件，但是当我在使用 ISA 服务器 2004 作为防火墙的域中使用它时，我的代码只显示邮箱有多少消息然后去等待

请任何人告诉我为什么以及我应该怎么做才能解决这个问题..

这是代码

public bool DownloadEmailWithAttachment(string Type)
    {
        try
        {
            EventLog.WriteEntry("Service", "Attachment Path :> " + AttachmentDir);
            long count = 0;
            Pop3Client email = new Pop3Client(UserName, Password, IncomingPopAddress);
            email.OpenInbox();                
            //LogEntry();
            EventLog.WriteEntry("Service", "Counter :> " + email.MessageCount);
            while (email.NextEmail())
            {
                count = email.MessageCount;
                if (email.IsMultipart)
                {

                    IEnumerator enumerator = email.MultipartEnumerator;
                    while (enumerator.MoveNext())
                    {
                        Pop3Component multipart = (Pop3Component)enumerator.Current;
                        string checkIfFile = multipart.Filename;

                        if (checkIfFile != null)
                        {
                            //Console.WriteLine("checkIfFile.Contains('Leave') =" + checkIfFile.ToString());
                            EventLog.WriteEntry("Service", "checkIfFile.Contains('"+Type+"') =" + checkIfFile.ToString());
                            if (checkIfFile.Contains(""+Type))
                            {
                                EventLog.WriteEntry("Service", "Attachment name=" + multipart.Name); // ... etc
                                byte[] filebytes = Encoding.ASCII.GetBytes(multipart.Data);

                                //Search FileName
                                int fileLength = checkIfFile.Length;
                                EventLog.WriteEntry("Service", "fileLength=" + fileLength);
                                //int Begin = multipart.ContentType.IndexOf("name="+checkIfFile.ToString());
                                string leFileNale = checkIfFile.ToString();
                                EventLog.WriteEntry("Service", leFileNale);
                                FileStream LeFS = new FileStream(AttachmentDir + "\\" + leFileNale, FileMode.Create, FileAccess.Write, FileShare.None);
                                LeFS.Write(filebytes, 0, filebytes.Length);
                                LeFS.Close();
                                string DeleteMailContainingSubject = email.Subject.ToString();
                                if (email.Subject.Contains(DeleteMailContainingSubject))
                                {
                                    email.DeleteEmail();
                                    EventLog.WriteEntry("Service", "Email with Subject " + DeleteMailContainingSubject);
                                }
                            }
                        }
                    }
                }
            }                
            email.CloseConnection();
        }
        catch (Pop3LoginException ex)
        {
            EventLog.WriteEntry("Service","Exception :" + ex.ToString());
        }
        return true;
    }

这是我下载电子邮件附件的代码。