đọc email pop3 từ server Mail (source C#)

Diễn đàn Dotnet framework đọc email pop3 từ server Mail (source C#)

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dotnetvn dotnet.vn 72 bài	01-01-2010 11:20:48 Code đã được kiểm tra chạy khá ổn định anh em ạ // POP3 Client // =========== // // copyright by Peter Huber, Singapore, 2006 // this code is provided as is, bugs are probable, free for any use, no responsibility accepted :-) // // based on POP3 Client as a C# Class, by Bill Dean, http://www.codeproject.com/csharp/Pop3MailClient.asp // based on Retrieve Mail From a POP3 Server Using C#, by Agus Kurniawan, http://www.codeproject.com/csharp/popapp.asp // based on Post Office Protocol - Version 3, http://www.ietf.org/rfc/rfc1939.txt using System; using System.Collections.Generic; using System.IO; using System.Net; using System.Net.Sockets; using System.Net.Security; using System.Text; namespace POP { // Supporting classes and structs // ============================== /// <summary> /// Combines Email ID with Email UID for one email /// The POP3 server assigns to each message a unique Email UID, which will not change for the life time /// of the message and no other message should use the same. /// /// Exceptions: /// Throws Pop3Exception if there is a serious communication problem with the POP3 server, otherwise /// /// </summary> public struct EmailUid { /// <summary> /// used in POP3 commands to indicate which message (only valid in the present session) /// </summary> public int EmailId; /// <summary> /// Uid is always the same for a message, regardless of session /// </summary> public string Uid; /// <summary> /// /// </summary> /// <param name="EmailId"></param> /// <param name="Uid"></param> public EmailUid(int EmailId, string Uid) { this.EmailId = EmailId; this.Uid = Uid; } } /// <summary> /// If anything goes wrong within Pop3MailClient, a Pop3Exception is raised /// </summary> public class Pop3Exception:ApplicationException { /// <summary> /// /// </summary> public Pop3Exception() { } /// <summary> /// /// </summary> /// <param name="ErrorMessage"></param> public Pop3Exception(string ErrorMessage) : base(ErrorMessage) { } } /// <summary> /// A pop 3 connection goes through the following states: /// </summary> public enum Pop3ConnectionStateEnum { /// <summary> /// undefined /// </summary> None=0, /// <summary> /// not connected yet to POP3 server /// </summary> Disconnected, /// <summary> /// TCP connection has been opened and the POP3 server has sent the greeting. POP3 server expects user name and password /// </summary> Authorization, /// <summary> /// client has identified itself successfully with the POP3, server has locked all messages /// </summary> Connected, /// <summary> /// QUIT command was sent, the server has deleted messages marked for deletion and released the resources /// </summary> Closed } // Delegates for Pop3MailClient // ============================ /// <summary> /// If POP3 Server doesn't react as expected or this code has a problem, but /// can continue with the execution, a Warning is called. /// </summary> /// <param name="WarningText"></param> /// <param name="Response">string received from POP3 server</param> public delegate void WarningHandler(string WarningText, string Response); /// <summary> /// Traces all the information exchanged between POP3 client and POP3 server plus some /// status messages from POP3 client. /// Helpful to investigate any problem. /// Console.WriteLine() can be used /// </summary> /// <param name="TraceText"></param> public delegate void TraceHandler(string TraceText); // Pop3MailClient Class // ==================== /// <summary> /// provides access to emails on a POP3 Server /// </summary> public class Pop3MailClient { //Events //------ /// <summary> /// Called whenever POP3 server doesn't react as expected, but no runtime error is thrown. /// </summary> public event WarningHandler Warning; /// <summary> /// call warning event /// </summary> /// <param name="methodName">name of the method where warning is needed</param> /// <param name="response">answer from POP3 server causing the warning</param> /// <param name="warningText">explanation what went wrong</param> /// <param name="warningParameters"></param> protected void CallWarning(string methodName, string response, string warningText, params object [] warningParameters) { warningText = string.Format(warningText, warningParameters); if (Warning!=null) { Warning(methodName + ": " + warningText, response); } CallTrace("!! {0}", warningText); } /// <summary> /// Shows the communication between PopClient and PopServer, including warnings /// </summary> public event TraceHandler Trace; /// <summary> /// call Trace event /// </summary> /// <param name="text">string to be traced</param> /// <param name="parameters"></param> protected void CallTrace(string text, params object [] parameters) { if (Trace!=null) { Trace(DateTime.Now.ToString("hh:mm:ss ") + popServer + " " + string.Format(text, parameters)); } } /// <summary> /// Trace information received from POP3 server /// </summary> /// <param name="text">string to be traced</param> /// <param name="parameters"></param> protected void TraceFrom(string text, params object [] parameters) { if (Trace!=null) { CallTrace(" " + string.Format(text, parameters)); } } //Properties //---------- /// <summary> /// Get POP3 server name /// </summary> public string PopServer { get { return popServer; } } /// <summary> /// POP3 server name /// </summary> protected string popServer; /// <summary> /// Get POP3 server port /// </summary> public int Port { get { return port; } } /// <summary> /// POP3 server port /// </summary> protected int port; /// <summary> /// Should SSL be used for connection with POP3 server ? /// </summary> public bool UseSSL { get { return useSSL; } } /// <summary> /// Should SSL be used for connection with POP3 server ? /// </summary> private bool useSSL; /// <summary> /// should Pop3MailClient automatically reconnect if POP3 server has dropped the /// connection due to a timeout ? /// </summary> public bool IsAutoReconnect { get { return isAutoReconnect; } set { isAutoReconnect = value; } } private bool isAutoReconnect = false; //timeout has occured, we try to perform an autoreconnect private bool isTimeoutReconnect = false; /// <summary> /// Get / set read timeout (miliseconds) /// </summary> public int ReadTimeout { get { return readTimeout; } set { readTimeout = value; if (pop3Stream!=null && pop3Stream.CanTimeout) { pop3Stream.ReadTimeout = readTimeout; } } } /// <summary> /// POP3 server read timeout /// </summary> protected int readTimeout = -1; /// <summary> /// Get owner name of mailbox on POP3 server /// </summary> public string Username { get { return username; } } /// <summary> /// Owner name of mailbox on POP3 server /// </summary> protected string username; /// <summary> /// Get password for mailbox on POP3 server /// </summary> public string Password { get { return password; } } /// <summary> /// Password for mailbox on POP3 server /// </summary> protected string password; /// <summary> /// Get connection status with POP3 server /// </summary> public Pop3ConnectionStateEnum Pop3ConnectionState { get { return pop3ConnectionState; } } /// <summary> /// connection status with POP3 server /// </summary> protected Pop3ConnectionStateEnum pop3ConnectionState = Pop3ConnectionStateEnum.Disconnected; // Methods // ------- /// <summary> /// set POP3 connection state /// </summary> /// <param name="State"></param> protected void setPop3ConnectionState(Pop3ConnectionStateEnum State) { pop3ConnectionState = State; CallTrace(" Pop3MailClient Connection State {0} reached", State); } /// <summary> /// throw exception if POP3 connection is not in the required state /// </summary> /// <param name="requiredState"></param> protected void EnsureState(Pop3ConnectionStateEnum requiredState) { if (pop3ConnectionState!=requiredState) { // wrong connection state throw new Pop3Exception("GetMailboxStats only accepted during connection state: " + requiredState.ToString() + "\n The connection to server "+ popServer + " is in state " + pop3ConnectionState.ToString()); } } //private fields //-------------- /// <summary> /// TCP to POP3 server /// </summary> private TcpClient serverTcpConnection; /// <summary> /// Stream from POP3 server with or without SSL /// </summary> private Stream pop3Stream; /// <summary> /// Reader for POP3 message /// </summary> protected StreamReader pop3StreamReader; /// <summary> /// char 'array' for carriage return / line feed /// </summary> protected string CRLF = "\r\n"; //public methods //-------------- /// <summary> /// Make POP3 client ready to connect to POP3 server /// </summary> /// <param name="PopServer"><example>pop.gmail.com</example></param> /// <param name="Port"><example>995</example></param> /// <param name="useSSL">True: SSL is used for connection to POP3 server</param> /// <param name="Username"><example>abc@gmail.com</example></param> /// <param name="Password">Secret</param> public Pop3MailClient(string PopServer, int Port, bool useSSL, string Username, string Password) { this.popServer = PopServer; this.port = Port; this.useSSL = useSSL; this.username = Username; this.password = Password; } /// <summary> /// Connect to POP3 server /// </summary> public void Connect() { if (pop3ConnectionState!=Pop3ConnectionStateEnum.Disconnected && pop3ConnectionState!=Pop3ConnectionStateEnum.Closed && !isTimeoutReconnect) { CallWarning("connect", "", "Connect command received, but connection state is: " + pop3ConnectionState.ToString()); } else { //establish TCP connection try { CallTrace(" Connect at port {0}", port); serverTcpConnection = new TcpClient(popServer, port); } catch (Exception ex) { throw new Pop3Exception("Connection to server "+ popServer + ", port " + port + " failed.\nRuntime Error: "+ex.ToString()); } if (useSSL) { //get SSL stream try { CallTrace(" Get SSL connection"); pop3Stream = new SslStream(serverTcpConnection.GetStream(), false); pop3Stream.ReadTimeout = readTimeout; } catch (Exception ex) { throw new Pop3Exception("Server " + popServer + " found, but cannot get SSL data stream.\nRuntime Error: "+ex.ToString()); } //perform SSL authentication try { CallTrace(" Get SSL authentication"); ((SslStream)pop3Stream).AuthenticateAsClient(popServer); } catch (Exception ex) { throw new Pop3Exception("Server " + popServer + " found, but problem with SSL Authentication.\nRuntime Error: " + ex.ToString()); } } else { //create a stream to POP3 server without using SSL try { CallTrace(" Get connection without SSL"); pop3Stream = serverTcpConnection.GetStream(); pop3Stream.ReadTimeout = readTimeout; } catch (Exception ex) { throw new Pop3Exception("Server " + popServer + " found, but cannot get data stream (without SSL).\nRuntime Error: "+ex.ToString()); } } //get stream for reading from pop server //POP3 allows only US-ASCII. The message will be translated in the proper encoding in a later step try { pop3StreamReader= new StreamReader(pop3Stream, Encoding.ASCII); } catch (Exception ex) { if (useSSL) { throw new Pop3Exception("Server " + popServer + " found, but cannot read from SSL stream.\nRuntime Error: " + ex.ToString()); } else { throw new Pop3Exception("Server " + popServer + " found, but cannot read from stream (without SSL).\nRuntime Error: " + ex.ToString()); } } //ready for authorisation string response; if (!readSingleLine(out response)) { throw new Pop3Exception("Server " + popServer + " not ready to start AUTHORIZATION.\nMessage: " + response); } setPop3ConnectionState(Pop3ConnectionStateEnum.Authorization); //send user name if (!executeCommand("USER "+ username, out response)) { throw new Pop3Exception("Server " + popServer + " doesn't accept username '" + username + "'.\nMessage: " + response); } //send password if (!executeCommand("PASS " + password, out response)) { throw new Pop3Exception("Server " + popServer + " doesn't accept password '" + password + "' for user '" + username + "'.\nMessage: " + response); } setPop3ConnectionState(Pop3ConnectionStateEnum.Connected); } } /// <summary> /// Disconnect from POP3 Server /// </summary> public void Disconnect() { if (pop3ConnectionState==Pop3ConnectionStateEnum.Disconnected \|\| pop3ConnectionState==Pop3ConnectionStateEnum.Closed) { CallWarning("disconnect", "", "Disconnect received, but was already disconnected."); } else { //ask server to end session and possibly to remove emails marked for deletion try { string response; if (executeCommand("QUIT", out response)) { //server says everything is ok setPop3ConnectionState(Pop3ConnectionStateEnum.Closed); } else { //server says there is a problem CallWarning("Disconnect", response, "negative response from server while closing connection: " + response); setPop3ConnectionState(Pop3ConnectionStateEnum.Disconnected); } } finally { //close connection if (pop3Stream!=null) { pop3Stream.Close(); } pop3StreamReader.Close(); } } } /// <summary> /// Delete message from server. /// The POP3 server marks the message as deleted. Any future /// reference to the message-number associated with the message /// in a POP3 command generates an error. The POP3 server does /// not actually delete the message until the POP3 session /// enters the UPDATE state. /// </summary> /// <param name="msg_number"></param> /// <returns></returns> public bool DeleteEmail(int msg_number) { EnsureState(Pop3ConnectionStateEnum.Connected); string response; if (!executeCommand("DELE " + msg_number.ToString(), out response)) { CallWarning("DeleteEmail", response, "negative response for email (Id: {0}) delete request", msg_number); return false; } return true; } /// <summary> /// Get a list of all Email IDs available in mailbox /// </summary> /// <returns></returns> public bool GetEmailIdList(out List<int> EmailIds) { EnsureState(Pop3ConnectionStateEnum.Connected); EmailIds = new List<int>(); //get server response status line string response; if (!executeCommand("LIST", out response)) { CallWarning("GetEmailIdList", response, "negative response for email list request"); return false; } //get every email id int EmailId; while (readMultiLine(out response)) { if (int.TryParse(response.Split(' ') [0] , out EmailId)) { EmailIds.Add(EmailId); } else { CallWarning("GetEmailIdList", response, "first characters should be integer (EmailId)"); } } TraceFrom("{0} email ids received", EmailIds.Count); return true; } /// <summary> /// get size of one particular email /// </summary> /// <param name="msg_number"></param> /// <returns></returns> public int GetEmailSize(int msg_number) { EnsureState(Pop3ConnectionStateEnum.Connected); string response; executeCommand("LIST " + msg_number.ToString(), out response); int EmailSize = 0; string [] responseSplit = response.Split(' '); if (responseSplit.Length<2 \|\| !int.TryParse(responseSplit [2] , out EmailSize)) { CallWarning("GetEmailSize", response, "'+OK int int' format expected (EmailId, EmailSize)"); } return EmailSize; } /// <summary> /// Get a list with the unique IDs of all Email available in mailbox. /// /// Explanation: /// EmailIds for the same email can change between sessions, whereas the unique Email id /// never changes for an email. /// </summary> /// <param name="EmailIds"></param> /// <returns></returns> public bool GetUniqueEmailIdList(out List<EmailUid> EmailIds) { EnsureState(Pop3ConnectionStateEnum.Connected); EmailIds = new List<EmailUid>(); //get server response status line string response; if (!executeCommand("UIDL ", out response)) { CallWarning("GetUniqueEmailIdList", response, "negative response for email list request"); return false; } //get every email unique id int EmailId; while (readMultiLine(out response)) { string [] responseSplit = response.Split(' '); if (responseSplit.Length<2) { CallWarning("GetUniqueEmailIdList", response, "response not in format 'int string'"); } else if (!int.TryParse(responseSplit [0] , out EmailId)) { CallWarning("GetUniqueEmailIdList", response, "first charaters should be integer (Unique EmailId)"); } else { EmailIds.Add(new EmailUid(EmailId, responseSplit [1] )); } } TraceFrom("{0} unique email ids received", EmailIds.Count); return true; } /// <summary> /// get a list with all currently available messages and the UIDs /// </summary> /// <param name="EmailIds">EmailId Uid list</param> /// <returns>false: server sent negative response (didn't send list)</returns> public bool GetUniqueEmailIdList(out SortedList<string, int> EmailIds) { EnsureState(Pop3ConnectionStateEnum.Connected); EmailIds = new SortedList<string, int>(); //get server response status line string response; if (!executeCommand("UIDL", out response)) { CallWarning("GetUniqueEmailIdList", response, "negative response for email list request"); return false; } //get every email unique id int EmailId; while (readMultiLine(out response)) { string [] responseSplit = response.Split(' '); if (responseSplit.Length<2) { CallWarning("GetUniqueEmailIdList", response, "response not in format 'int string'"); } else if (!int.TryParse(responseSplit [0] , out EmailId)) { CallWarning("GetUniqueEmailIdList", response, "first charaters should be integer (Unique EmailId)"); } else { EmailIds.Add(responseSplit [1] , EmailId); } } TraceFrom("{0} unique email ids received", EmailIds.Count); return true; } /// <summary> /// get size of one particular email /// </summary> /// <param name="msg_number"></param> /// <returns></returns> public int GetUniqueEmailId(EmailUid msg_number) { EnsureState(Pop3ConnectionStateEnum.Connected); string response; executeCommand("LIST " + msg_number.ToString(), out response); int EmailSize = 0; string [] responseSplit = response.Split(' '); if (responseSplit.Length<2 \|\| !int.TryParse(responseSplit [2] , out EmailSize)) { CallWarning("GetEmailSize", response, "'+OK int int' format expected (EmailId, EmailSize)"); } return EmailSize; } /// <summary> /// Sends an 'empty' command to the POP3 server. Server has to respond with +OK /// </summary> /// <returns>true: server responds as expected</returns> public bool NOOP() { EnsureState(Pop3ConnectionStateEnum.Connected); string response; if (!executeCommand("NOOP", out response)) { CallWarning("NOOP", response, "negative response for NOOP request"); return false; } return true; } /// <summary> /// Should the raw content, the US-ASCII code as received, be traced /// GetRawEmail will switch it on when it starts and off once finished /// /// Inheritors might use it to get the raw email /// </summary> protected bool isTraceRawEmail = false; /// <summary> /// contains one MIME part of the email in US-ASCII, needs to be translated in .NET string (Unicode) /// contains the complete email in US-ASCII, needs to be translated in .NET string (Unicode) /// For speed reasons, reuse StringBuilder /// </summary> protected StringBuilder RawEmailSB; /// <summary> /// Reads the complete text of a message /// </summary> /// <param name="MessageNo">Email to retrieve</param> /// <param name="EmailText">ASCII string of complete message</param> /// <returns></returns> public bool GetRawEmail(int MessageNo, out string EmailText) { //send 'RETR int' command to server if (!SendRetrCommand(MessageNo)) { EmailText = null; return false; } //get the lines string response; int LineCounter = 0; //empty StringBuilder if (RawEmailSB==null) { RawEmailSB = new StringBuilder(100000); } else { RawEmailSB.Length = 0; } isTraceRawEmail = true; while (readMultiLine(out response)) { LineCounter += 1; } EmailText = RawEmailSB.ToString(); TraceFrom("email with {0} lines, {1} chars received", LineCounter.ToString(), EmailText.Length); return true; } ///// <summary> ///// Requests from POP3 server a specific email and returns a stream with the message content (header and body) ///// </summary> ///// <param name="MessageNo"></param> ///// <param name="EmailStreamReader"></param> ///// <returns>false: POP3 server cannot provide this message</returns> //public bool GetEmailStream(int MessageNo, out StreamReader EmailStreamReader) { // //send 'RETR int' command to server // if (!SendRetrCommand(MessageNo)) { // EmailStreamReader = null; // return false; // } // EmailStreamReader = sslStreamReader; // return true; //} /// <summary> /// Unmark any emails from deletion. The server only deletes email really /// once the connection is properly closed. /// </summary> /// <returns>true: emails are unmarked from deletion</returns> public bool UndeleteAllEmails() { EnsureState(Pop3ConnectionStateEnum.Connected); string response; return executeCommand("RSET", out response); } /// <summary> /// Get mailbox statistics /// </summary> /// <param name="NumberOfMails"></param> /// <param name="MailboxSize"></param> /// <returns></returns> public bool GetMailboxStats(out int NumberOfMails, out int MailboxSize) { EnsureState(Pop3ConnectionStateEnum.Connected); //interpret response string response; NumberOfMails = 0; MailboxSize =0; if (executeCommand("STAT", out response)) { //got a positive response string [] responseParts = response.Split(' '); if (responseParts.Length<2) { //response format wrong throw new Pop3Exception("Server " + popServer + " sends illegally formatted response." + "\nExpected format: +OK int int" + "\nReceived response: " + response); } NumberOfMails = int.Parse(responseParts [1] ); MailboxSize = int.Parse(responseParts [2] ); return true; } return false; } /// <summary> /// Send RETR command to POP 3 server to fetch one particular message /// </summary> /// <param name="MessageNo">ID of message required</param> /// <returns>false: negative server respond, message not delivered</returns> protected bool SendRetrCommand(int MessageNo) { EnsureState(Pop3ConnectionStateEnum.Connected); // retrieve mail with message number string response; if (!executeCommand("RETR "+ MessageNo.ToString(), out response)) { CallWarning("GetRawEmail", response, "negative response for email (ID: {0}) request", MessageNo); return false; } return true; } //Helper methodes //--------------- /// <summary> /// sends the 4 letter command to POP3 server (adds CRLF) and waits for the /// response of the server /// </summary> /// <param name="command">command to be sent to server</param> /// <param name="response">answer from server</param> /// <returns>false: server sent negative acknowledge, i.e. server could not execute command</returns> public bool isDebug = false; private bool executeCommand(string command, out string response) { //send command to server byte [] commandBytes = System.Text.Encoding.ASCII.GetBytes((command + CRLF).ToCharArray()); CallTrace("Tx '{0}'", command); bool isSupressThrow = false; try { pop3Stream.Write(commandBytes, 0, commandBytes.Length); if (isDebug) { isDebug=false; throw new IOException("Test", new SocketException(10053)); } } catch (IOException ex) { //Unable to write data to the transport connection. Check if reconnection should be tried isSupressThrow = executeReconnect(ex, command, commandBytes); if (!isSupressThrow) { throw; } } pop3Stream.Flush(); //read response from server response = null; try { response = pop3StreamReader.ReadLine(); } catch (IOException ex) { //Unable to write data to the transport connection. Check if reconnection should be tried isSupressThrow = executeReconnect(ex, command, commandBytes); if (isSupressThrow) { //wait for response one more time response = pop3StreamReader.ReadLine(); } else { throw; } } if (response==null) { throw new Pop3Exception("Server "+ popServer + " has not responded, timeout has occured."); } CallTrace("Rx '{0}'", response); return (response.Length>0 && response [0] =='+'); } /// <summary> /// reconnect, if there is a timeout exception and isAutoReconnect is true /// /// </summary> private bool executeReconnect(IOException ex, string command, byte [] commandBytes) { if (ex.InnerException!=null && ex.InnerException is SocketException) { //SocketException SocketException innerEx = (SocketException)ex.InnerException; if (innerEx.ErrorCode==10053) { //probably timeout: An established connection was aborted by the software in your host machine. CallWarning("ExecuteCommand", "", "probably timeout occured"); if (isAutoReconnect) { //try to reconnect and send one more time isTimeoutReconnect = true; try { CallTrace(" try to auto reconnect"); Connect(); CallTrace(" reconnect successful, try to resend command"); CallTrace("Tx '{0}'", command); pop3Stream.Write(commandBytes, 0, commandBytes.Length); pop3Stream.Flush(); return true; } finally { isTimeoutReconnect = false; } } } } return false; } /* /// <summary> /// sends the 4 letter command to POP3 server (adds CRLF) /// </summary> /// <param name="command"></param> protected void SendCommand(string command) { byte [] commandBytes = System.Text.Encoding.ASCII.GetBytes((command + CRLF).ToCharArray()); CallTrace("Tx '{0}'", command); try { pop3Stream.Write(commandBytes, 0, commandBytes.Length); } catch (IOException ex) { //Unable to write data to the transport connection: if (ex.InnerException!=null && ex.InnerException is SocketException) { //SocketException SocketException innerEx = (SocketException)ex.InnerException; if (innerEx.ErrorCode==10053) { //probably timeout: An established connection was aborted by the software in your host machine. CallWarning("SendCommand", "", "probably timeout occured"); if (isAutoReconnect) { //try to reconnect and send one more time isTimeoutReconnect = true; try { CallTrace(" try to auto reconnect"); Connect(); CallTrace(" reconnect successful, try to resend command"); CallTrace("Tx '{0}'", command); pop3Stream.Write(commandBytes, 0, commandBytes.Length); } finally { isTimeoutReconnect = false; } return; } } } throw; } pop3Stream.Flush(); } */ /// <summary> /// read single line response from POP3 server. /// <example>Example server response: +OK asdfkjahsf</example> /// </summary> /// <param name="response">response from POP3 server</param> /// <returns>true: positive response</returns> protected bool readSingleLine(out string response) { response = null; try { response = pop3StreamReader.ReadLine(); } catch (Exception ex) { string s = ex.Message; } if (response==null) { throw new Pop3Exception("Server "+ popServer + " has not responded, timeout has occured."); } CallTrace("Rx '{0}'", response); return (response.Length>0 && response [0] =='+'); } /// <summary> /// read one line in multiline mode from the POP3 server. /// </summary> /// <param name="response">line received</param> /// <returns>false: end of message</returns> /// <returns></returns> protected bool readMultiLine(out string response) { response = null; response = pop3StreamReader.ReadLine(); if (response==null) { throw new Pop3Exception("Server "+ popServer + " has not responded, probably timeout has occured."); } if (isTraceRawEmail) { //collect all responses as received RawEmailSB.Append(response + CRLF); } //check for byte stuffing, i.e. if a line starts with a '.', another '.' is added, unless //it is the last line if (response.Length>0 && response [0] =='.') { if (response==".") { //closing line found return false; } //remove the first '.' response = response.Substring(1, response.Length-1); } return true; } } }

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