当我的PC通过代理或无代理连接到互联网时，从Gmail，live，aol或yahoo帐户发送SMTP邮件

我想通过SMTP将C＃中的电子邮件发送到不同的邮件提供商示例Gmail，Yahoo，AOL，Msn，Live等，以便我的代码可以正常工作，如果我的计算机通过代理连接到互联网或直接连接到互联网 。 （代理是一个转发代理，从内部网络接收请求并将它们转发到Internet，我在IE中配置代理）
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如果没有通过代理连接PC，我有代码可以发送SMTP邮件

public void SendMail(string senderId, string password, List To, List CC, List BCC, string Subject, string Body, List Attachment) { SmtpClient SmtpServer = null; string[] ss = senderId.Split('@'); string ServerName = ss[1].Substring(0, ss[1].IndexOf(".")); switch (ServerName.ToLower()) { case "gmail": SmtpServer = new SmtpClient("smtp.gmail.com"); SmtpServer.Port = 587; SmtpServer.Credentials = new System.Net.NetworkCredential(senderId, password); SmtpServer.EnableSsl = true; break; case "msn": case "live": case "hotmail": case "outlook": SmtpServer = new SmtpClient("smtp.live.com"); SmtpServer.Port = 25; SmtpServer.Credentials = new System.Net.NetworkCredential(senderId, password); SmtpServer.EnableSsl = true; break; case "aol": SmtpServer = new SmtpClient("smtp.aol.com"); SmtpServer.Port = 25; SmtpServer.Credentials = new System.Net.NetworkCredential(senderId, password); SmtpServer.EnableSsl = true; break; case "yahoo": case "ymail": case "rocketmail": case "yahoomail": SmtpServer = new SmtpClient("smtp.mail.yahoo.com"); SmtpServer.Port = 25; SmtpServer.Credentials = new System.Net.NetworkCredential(senderId, password); SmtpServer.EnableSsl = false; break; default: break; } SmtpServer.DeliveryMethod = SmtpDeliveryMethod.Network; MailMessage mail = new MailMessage(); mail.From = new MailAddress(senderId); foreach (string item in To) { mail.To.Add(item); } foreach (string item in CC) { mail.CC.Add(item); } foreach (string item in BCC) { mail.Bcc.Add(item); } mail.Subject = Subject; mail.Body = Body; foreach (Attachment item in Attachment) { mail.Attachments.Add(item); } SmtpServer.Send(mail); } 

这工作得非常好，但我希望在通过代理连接时发送电子邮件。

我读了很多post，比如通过代理服务器发送邮件
ASP.net SMTP邮件通过代理
是否有通过PROXY发送电子邮件的.NET库？
他们都声明这是不可能的，但在搜索时我发现了chilkat库， limilabs示例允许用户通过配置代理来通过代理发送邮件。
我已经研究了很多，我已经阅读了SOCKS代理，学会了如何使用原始套接字发送SMTP邮件，但我无法找到丢失的解决方案。
如果有任何人遇到同样的问题或任何想法我能做什么，我会很感激以前做过的一些工作的想法吗？

编辑： –正如我已经提到的那样，我发现了使用Chilkat和limilabs的样本，这意味着我不想使用它们 ，我不允许使用任何第三方dll

Answer 1

通过代理服务器发送邮件有点棘手，但最后通过使用代码通过套接字发送邮件解决了问题。

在发布答案后期，但我们假设它可能对其他人有帮助。

从链接代码获取帮助

附加下面的代码， SmtpServer对象与上述描述相同，

  #region ..... SOCKET MAIL ..... private enum SMTPResponse : int { /// 
 /// 220 /// 
 CONNECT_SUCCESS = 220, /// 
 /// 235 /// 
 CRED_SUCCESS = 235, /// 
 /// 250 /// 
 GENERIC_SUCCESS = 250, /// 
 /// 334 /// 
 AUTH_SUCCESS = 334, /// 
 /// 354 /// 
 DATA_SUCCESS = 354, /// 
 /// 221 /// 
 QUIT_SUCCESS = 221 } public static string EncodeTo64(string toEncode) { byte[] toEncodeAsBytes = System.Text.Encoding.ASCII.GetBytes(toEncode); string returnValue = System.Convert.ToBase64String(toEncodeAsBytes, Base64FormattingOptions.None); return returnValue; } public bool SendFromSocket(MailMessage message) { var requestUri = new System.Uri("smtps://" +SmtpServer.Host +":"+SmtpServer.Port); Uri proxy = null; //This is magic code which does your job for the proxy using (var web = new System.Net.WebClient()) { proxy = web.Proxy.GetProxy(requestUri); } using (var s = new TcpClient(proxy.DnsSafeHost, proxy.Port )) { using (var stream = s.GetStream()) using (var clearTextReader = new StreamReader(stream)) using (var clearTextWriter = new StreamWriter(stream) { AutoFlush = true }) using (var sslStream = new SslStream(stream)) { if (!Check_Response(clearTextReader, SMTPResponse.CONNECT_SUCCESS)) { s.Close(); return false; } clearTextWriter.WriteLine("HELO"); if (!Check_Response(clearTextReader, SMTPResponse.GENERIC_SUCCESS)) { s.Close(); return false; } clearTextWriter.WriteLine("STARTTLS"); if (!Check_Response(clearTextReader, SMTPResponse.CONNECT_SUCCESS)) { s.Close(); return false; } sslStream.AuthenticateAsClient(SmtpServer.Host); bool flag = sslStream.IsAuthenticated; using (var reader = new StreamReader(sslStream)) using (var writer = new StreamWriter(sslStream) { AutoFlush = true }) { writer.WriteLine(string.Format("EHLO {0}", SmtpServer.Host)); if (!Check_Response(reader, SMTPResponse.GENERIC_SUCCESS)) { s.Close(); return false; } writer.WriteLine("AUTH LOGIN"); if (!Check_Response(reader, SMTPResponse.AUTH_SUCCESS)) { s.Close(); return false; } writer.WriteLine(EncodeTo64(SenderId)); if (!Check_Response(reader, SMTPResponse.AUTH_SUCCESS)) { s.Close(); return false; } writer.WriteLine(EncodeTo64(Password)); if (!Check_Response(reader, SMTPResponse.CRED_SUCCESS)) { s.Close(); return false; } writer.WriteLine("MAIL FROM: <{0}>", message.From); if (!Check_Response(reader, SMTPResponse.GENERIC_SUCCESS)) { s.Close(); return false; } foreach (MailAddress To in message.To) { writer.WriteLine("RCPT TO: <{0}>", To.Address); if (!Check_Response(reader, SMTPResponse.GENERIC_SUCCESS)) { s.Close(); return false; } } if (message.CC != null) { foreach (MailAddress cc in message.CC) { writer.WriteLine(string.Format("RCPT TO: <{0}>", cc.Address)); if (!Check_Response(reader, SMTPResponse.GENERIC_SUCCESS)) { s.Close(); return false; } } } StringBuilder Header = new StringBuilder(); Header.Append("From: " + message.From + "\r\n"); Header.Append("To: "); for (int i = 0; i < message.To.Count; i++) { Header.Append(i > 0 ? "," : ""); Header.Append(message.To[i].Address); } Header.Append("\r\n"); if (message.CC != null) { Header.Append("Cc: "); for (int i = 0; i < message.CC.Count; i++) { Header.Append(i > 0 ? "," : ""); Header.Append(message.CC[i].Address); } Header.Append("\r\n"); } Header.Append("Date: "); Header.Append(DateTime.Now.ToString("ddd, d M y H:m:sz")); Header.Append("\r\n"); Header.Append("Subject: " + message.Subject + "\r\n"); Header.Append("X-Mailer: SMTPDirect v1\r\n"); string MsgBody = message.Body; if (!MsgBody.EndsWith("\r\n")) MsgBody += "\r\n"; if (message.Attachments.Count > 0) { Header.Append("MIME-Version: 1.0\r\n"); Header.Append("Content-Type: multipart/mixed; boundary=unique-boundary-1\r\n"); Header.Append("\r\n"); Header.Append("This is a multi-part message in MIME format.\r\n"); StringBuilder sb = new StringBuilder(); sb.Append("--unique-boundary-1\r\n"); sb.Append("Content-Type: text/plain\r\n"); sb.Append("Content-Transfer-Encoding: 7Bit\r\n"); sb.Append("\r\n"); sb.Append(MsgBody + "\r\n"); sb.Append("\r\n"); foreach (object o in message.Attachments) { Attachment a = o as Attachment; byte[] binaryData; if (a != null) { //FileInfo f = new FileInfo(a.); sb.Append("--unique-boundary-1\r\n"); sb.Append("Content-Type: application/octet-stream; file=" + a.Name + "\r\n"); sb.Append("Content-Transfer-Encoding: base64\r\n"); sb.Append("Content-Disposition: attachment; filename=" + a.Name + "\r\n"); sb.Append("\r\n"); Stream fs = a.ContentStream; binaryData = new Byte[fs.Length]; long bytesRead = fs.Read(binaryData, 0, (int)fs.Length); fs.Close(); string base64String = System.Convert.ToBase64String(binaryData, 0, binaryData.Length); for (int i = 0; i < base64String.Length; ) { int nextchunk = 100; if (base64String.Length - (i + nextchunk) < 0) nextchunk = base64String.Length - i; sb.Append(base64String.Substring(i, nextchunk)); sb.Append("\r\n"); i += nextchunk; } sb.Append("\r\n"); } } MsgBody = sb.ToString(); } writer.WriteLine("DATA\r\n"); if (!Check_Response(reader, SMTPResponse.DATA_SUCCESS)) { s.Close(); return false; } Header.Append("\r\n"); Header.Append(MsgBody); Header.Append(".\r\n"); Header.Append("\r\n"); Header.Append("\r\n"); writer.WriteLine(Header.ToString()); if (!Check_Response(reader, SMTPResponse.GENERIC_SUCCESS)) { s.Close(); return false; } writer.WriteLine("QUIT\r\n"); Check_Response(reader, SMTPResponse.QUIT_SUCCESS); s.Close(); return true; } } } } private static bool Check_Response(StreamReader netStream, SMTPResponse response_expected) { int response; int read = 0; StringBuilder sResponse = new StringBuilder(); do { char[] buffer = new char[1024]; read = netStream.Read(buffer, 0, buffer.Length); sResponse.Append(buffer); } while (read == 1024); response = Convert.ToInt32(sResponse.ToString().Substring(0, 3)); if (response != (int)response_expected) return false; return true; } #endregion ..... SOCKET MAIL .....