sending emails on behalf of

Question

I am writing an email application that allows for news letter to be sent. i need to be able to set the email header so that the recipient sees emailfrom@emailaddress on behalf of i am sending this through an smtp server. i have the emails working but i can not get the on behalf of to work. i am not using the cdosys object or the webmail object in .net but talking direct to the smtp server. does anyone know what the command is that i need to send to the server to set it so that i can? here is the class that i am using in the code i tried the sender: command but that caused an error. any thoughts or help would be appreciated. i think i missing something very simple! using System; using System.Collections; using System.Net; using System.Net.Sockets; using System.Text; namespace email { public class SmtpException : ApplicationException { public SmtpException(string message) : base(message) { } } /// /// Indicates the type of message to be sent /// public enum MessageType { /// /// The message is plain text /// Text = 0, /// /// The message is HTML /// HTML = 1 } /// /// A mail message that can be sent using the Smtp class /// public class MailMessage { private string _emailFrom = ""; public string EmailFrom { get { return _emailFrom; } set { _emailFrom = value; } } private string _emailSubject = ""; public string EmailSubject { get { return _emailSubject; } set { _emailSubject = value; } } private ArrayList _emailTo = null; public ArrayList EmailTo { get { return _emailTo; } } public void AddEmailTo(string email) { if(_emailTo == null) _emailTo = new ArrayList(); _emailTo.Add(email); } private string _emailMessage = ""; public string EmailMessage { get { return _emailMessage; } set { _emailMessage = value; } } private string _DisplayName = ""; public string DisplayName { get { return _DisplayName; } set { _DisplayName = value; } } // to be used for the on behalf of option in the email header private string _SenderName=""; public string SenderName { get {return _SenderName; } set { _SenderName = value; } } private string _SenderEmail=""; public string SenderEmail { get {return _SenderEmail; } set { _SenderEmail = value; } } private MessageType _emailMessageType = MessageType.Text; public MessageType EmailMessageType { get { return _emailMessageType; } set { _emailMessageType = value; } } } /// /// This class allows sending of e-mails through Smtp /// For help on SMTP, look up http://www.faqs.org/rfcs/rfc821.html /// public class Smtp { #region Class properties private string _serverSmtp = ""; public string SmtpServer { get { return _serverSmtp; } set { _serverSmtp = value; } } private int _portSmtp = 25; public int SmtpPort { get { return _portSmtp; } set { _portSmtp = value; } } private string _userSmtp = ""; public string SmtpUser { get { return _userSmtp; } set { _userSmtp = value; } } private string _passwordSmtp = ""; public string SmtpPassword { get { return _passwordSmtp; } set { _passwordSmtp = value; } } #endregion public Smtp() { } #region Public methods /// /// Sends the e-mail based on the properties set for this object /// public void SendEmail(MailMessage msg) { int code; if(_serverSmtp == "" || msg.EmailFrom == "" || msg.EmailSubject == "" || msg.EmailTo == null) { throw new SmtpException("Invalid Smtp or email parameters."); } // open a connection to the Smtp server using(TcpClient smtpSocket = new TcpClient(_serverSmtp, _portSmtp)) using(NetworkStream ns = smtpSocket.GetStream()) { // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 220) { throw new SmtpException("Error connecting to Smtp server. (" + code.ToString() + ")"); } // EHLO WriteBuffer(ns, "helo " + _serverSmtp + "\r\n"); // get response from Smtp server string buffer = ReadBuffer(ns); code = GetSmtpResponse(buffer); if(code != 250) { throw new SmtpException("Error initiating communication with Smtp server. (" + code.ToString() + ")"); } // check for AUTH=LOGIN if(buffer.IndexOf("AUTH=LOGIN") >= 0) { // AUTH LOGIN WriteBuffer(ns, "auth login\r\n"); // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 334) { //throw new SmtpException("Error initiating Auth=Login. (" + code.ToString() + ")"); } // username: WriteBuffer(ns, System.Convert.ToBase64String(ASCIIEncoding.ASCII.GetBytes(_userSmtp)) + "\r\n"); // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 334) { //throw new SmtpException("Error setting Auth user name. (" + code.ToString() + ")"); } // password: WriteBuffer(ns, System.Convert.ToBase64String(ASCIIEncoding.ASCII.GetBytes(_passwordSmtp)) + "\r\n"); // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 235) { //throw new SmtpException("Error setting Auth password. (" + code.ToString() + ")"); } } // MAIL FROM: WriteBuffer(ns, "mail from: <" + msg.EmailFrom + ">\r\n"); // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 250) { throw new SmtpException("Error setting sender email address. (" + code.ToString() + ")"); } // WriteBuffer(ns,"Sender: <" + msg.SenderEmail + ">\r\n"); // code = GetSmtpResponse(ReadBuffer(ns)); // if(code != 250) // { // throw new SmtpException("Error setting sender email address. (" + code.ToString() + ")"); // } // RCPT TO: foreach(string sEmailTo in msg.EmailTo) { WriteBuffer(ns, "rcpt to:<" + sEmailTo + ">\r\n"); // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 250 && code != 251) { throw new SmtpException("Error setting receipient email address. (" + code.ToString() + ")"); } } // DATA WriteBuffer(ns, "data\r\n"); // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 354) { throw new SmtpException("Error starting email body. (" + code.ToString() + ")"); } // Repeat the from and to addresses in the data section WriteBuffer(ns, "from:" + msg.DisplayName + "<" + msg.EmailFrom + ">\r\n"); //WriteBuffer(ns,"Sender:" + msg.SenderName + "<" + msg.SenderEmail + ">\r\n"); foreach(string sEmailTo in msg.EmailTo) { WriteBuffer(ns, "to:<" + sEmailTo + ">\r\n"); } WriteBuffer(ns, "Date:" + DateTime.UtcNow.ToString("r") + "\r\n"); //WriteBuffer(ns, "DATA:" + "X-Mailer: Internet Mail" + "\r\n"); WriteBuffer(ns, "Subject:" + msg.EmailSubject + "\r\n"); switch(msg.EmailMessageType) { case MessageType.Text: // send text message WriteBuffer(ns, "\r\n" + msg.EmailMessage + "\r\n.\r\n"); break; case MessageType.HTML: // send HTML message WriteBuffer(ns, "MIME-Version: 1.0\r\n"); WriteBuffer(ns, "Content-type: text/html\r\n"); WriteBuffer(ns, "\r\n" + msg.EmailMessage + "\r\n.\r\n"); break; } // get response from Smtp server code = GetSmtpResponse(ReadBuffer(ns)); if(code != 250) { throw new SmtpException("Error setting email body. (" + code.ToString() + ")"); } // QUIT WriteBuffer(ns, "quit\r\n"); } } #endregion #region Private methods /// /// Looks for an Smtp response code inside a repsonse string /// /// The response string to be searched /// The int value of the Smtp reponse code private int GetSmtpResponse(string sResponse) { int response = 0; int iSpace = sResponse.IndexOf(" "); int iDash = sResponse.IndexOf("-"); if(iDash > 0 && iDash < iSpace) iSpace = sResponse.IndexOf("-"); try { if(iSpace > 0) response = int.Parse(sResponse.Substring(0, iSpace)); } catch(Exception) { // error - ignore it } return response; } /// /// Write a string to the network stream /// /// The network stream on which to write /// The string to write to the stream private void WriteBuffer(NetworkStream ns, string sBuffer) { try { byte[] buffer = Encoding.ASCII.GetBytes(sBuffer); ns.Write(buffer, 0, buffer.Length); } catch(System.IO.IOException) { // error writing to stream throw new SmtpException("Error sending data to Smtp server."); } } /// /// Reads a response from the network stream /// /// The network stream from which to read /// A string representing the reponse read private string ReadBuffer(NetworkStream ns) { byte[] buffer = new byte[1024]; int i=0; int b; int timeout = System.Environment.TickCount; try { // wait for data to show up on the stream while(!ns.DataAvailable && ((System.Environment.TickCount - timeout) < 20000)) { System.Threading.Thread.Sleep(100); } if(!ns.DataAvailable) throw new SmtpException("No response received from Smtp server."); // read while there's data on the stream while(i < buffer.Length && ns.DataAvailable) { b = ns.ReadByte(); buffer[i++] = (byte)b; } } catch(System.IO.IOException) { // error reading from stream throw new SmtpException("Error receiving data from Smtp server."); } return Encoding.ASCII.GetString(buffer); } #endregion } }