I have written a web based front end for SMTP email program. This SMTP mail program is for .net beta 2 version and I have compiled it into a DLL. Then this DLL is accessed through aspx file which can be viewed in browser.
There is built in SMTP class already available in System.Web.Mail namespace . However it is worth taking a look at program below as it shows inner details of how to communicate with SMTP server. Once u grasp this technique, u can modify it communicate any TCP socket server like FTP (for file access), http(for web access), IRC (for chat) etc.
First of all, let's see SMTP mail client.
/*
Name : SMTPMail.cs
Description : SMTP email client .
Version : 1.0
Author : Ravindra Sadaphule
Email : [email protected]
Last Modified: 13th September , 2001
To compile: csc /t:library /out:SMTPMail.dll SMTPMail.cs
Note : save this file in c:/inetpub/wwwroot/bin directory
*/
namespace Ravindra
{
// SMTPClient is a class whicjh inherits from TcpClient . Hence it can access all protected and public membert of TcpClient
public class SMTPClient : System.Net.Sockets.TcpClient
{
public bool isConnected()
{
return Active ;
}
public void SendCommandToServer(string Command)
{
System.Net.Sockets.NetworkStream ns = this.GetStream() ;
byte[] WriteBuffer ;
WriteBuffer = new byte[1024] ;
System.Text.ASCIIEncoding en = new System.Text.ASCIIEncoding() ;
WriteBuffer = en.GetBytes(Command) ;
ns.Write(WriteBuffer,0,WriteBuffer.Length);
return ;
}
public string GetServerResponse()
{
int StreamSize ;
string ReturnValue = "" ;
byte[] ReadBuffer ;
System.Net.Sockets.NetworkStream ns = this.GetStream() ;
ReadBuffer = new byte[1024] ;
StreamSize = ns.Read(ReadBuffer,0,ReadBuffer.Length);
if (StreamSize==0)
{
return ReturnValue ;
}
else
{
System.Text.ASCIIEncoding en = new System.Text.ASCIIEncoding() ;
ReturnValue = en.GetString(ReadBuffer) ;
return ReturnValue;
}
}
public bool DoesStringContainSMTPCode(System.String s,System.String SMTPCode)
{
return (s.IndexOf(SMTPCode,0,10)==-1)?false:true ;
}
}// end of class SMTPClient
public class SMTPMail
{
private System.String _SMTPServerIP = "127.0.0.1" ;
private System.String _errmsg = "" ;
private System.String _ServerResponse = "" ;
private System.String _Identity = "expowin2k" ;
private System.String _MailFrom = "" ;
private System.String _MailTo = "" ;
private System.String _MailData = "" ;
private System.String _Subject = "" ;
public System.String Subject // This property contains Subject of email
{
set
{
_Subject = value ;
}
}
public System.String Identity // This property contains Sender's Identity
{
set
{
_Identity = value ;
}
}
public System.String MailFrom // This property contains sender's email address
{
set
{
_MailFrom = value ;
}
}
public System.String MailTo // This property contains recepient's email address
{
set
{
_MailTo = value ;
}
}
public System.String MailData // This property contains email message
{
set
{
_MailData = value ;
}
}
public System.String SMTPServerIP // This property contains IP address of SMTP server
{
get
{
return _SMTPServerIP ;
}
set
{
_SMTPServerIP = value ;
}
}
public System.String ErrorMessage // This property contais error message
{
get
{
return _errmsg ;
}
}
public System.String ServerResponse // This property contains SMTP server response
{
get
{
return _ServerResponse ;
}
}
public void SendMail()
{
try
{
System.String ServerResponse ;
SMTPClient tcp = new SMTPClient() ;
tcp.Connect(SMTPServerIP,25) ; // first connect to smtp server
bool blnConnect = tcp.isConnected();
// test for successful connection
if (!blnConnect)
{
// System.Console.WriteLine("connection failed...");
_errmsg = "Connetion Failed..." ;
return;
}
//read response of the server
ServerResponse = tcp.GetServerResponse() ;
if (tcp.DoesStringContainSMTPCode(ServerResponse,"220"))
{
_ServerResponse += ServerResponse ;
}
else
{
_errmsg = "connection failed" + ServerResponse ;
return ;
}
//String[] SendBuffer = {"HELO thravindras\r\n","MAIL FROM: megha@thravindras\r\n","RCPT TO: ravindras@expowin2k\r\n","DATA \r\n"," Blah Blah Blah This is test mail from ravindra\r\n.\r\n","QUIT\r\n"};
System.String[] SendBuffer = new System.String[6] ;;
System.String[] ResponseCode = {"220","250","251","354","221"}; // success codes from SMTP server
System.String StrTemp = "" ;
StrTemp = System.String.Concat("HELO ",_Identity);
StrTemp = System.String.Concat(StrTemp,"\r\n");
SendBuffer[0] = StrTemp ;
StrTemp = "" ;
StrTemp = System.String.Concat("MAIL FROM: ",_MailFrom);
StrTemp = System.String.Concat(StrTemp,"\r\n");
SendBuffer[1] = StrTemp ;
StrTemp = "" ;
StrTemp = System.String.Concat("RCPT TO: ",_MailTo);
StrTemp = System.String.Concat(StrTemp,"\r\n");
SendBuffer[2] = StrTemp ;
StrTemp = "" ;
StrTemp = System.String.Concat("DATA","\r\n");
SendBuffer[3] = StrTemp ;
StrTemp = "" ;
StrTemp = System.String.Concat("From: ",_MailFrom );
StrTemp = System.String.Concat(StrTemp,"\r\n" );
StrTemp = System.String.Concat(StrTemp,"To: " );
StrTemp = System.String.Concat(StrTemp,_MailTo);
StrTemp = System.String.Concat(StrTemp,"\r\n" );
StrTemp = System.String.Concat(StrTemp,"Subject: " );
StrTemp = System.String.Concat(StrTemp,_Subject);
StrTemp = System.String.Concat(StrTemp,"\r\n" );
StrTemp = System.String.Concat(StrTemp,_MailData);
StrTemp = System.String.Concat(StrTemp,"\r\n.\r\n");
SendBuffer[4] = StrTemp ;
StrTemp = "" ;
StrTemp = System.String.Concat(StrTemp,"QUIT\r\n");
SendBuffer[5] = StrTemp ;
int i = 0 ;
/* for debugging
_errmsg = "" ;
for(i=0;i<5;i++)
{
_errmsg += SendBuffer[i] ;
_errmsg += "<br>" ;
}
return ;
end of debugging
*/
while(i < SendBuffer.Length)
{
tcp.SendCommandToServer(SendBuffer[i]) ;
ServerResponse = tcp.GetServerResponse() ;
for(int j=0;j<ResponseCode.Length;j++)
{
if (tcp.DoesStringContainSMTPCode(ServerResponse,ResponseCode[j]))
{
_ServerResponse += ServerResponse;
_ServerResponse += "<br>";
break;
}
else
{
if(j==ResponseCode.Length-1)
{
_errmsg += ServerResponse ;
_errmsg += SendBuffer[i] ;
return ;
}
}
}
i++ ;
} // end of while loop ;
}
catch(System.Net.Sockets.SocketException se)
{
_errmsg += se.Message + " " + se.StackTrace;
}
catch(System.Exception e)
{
_errmsg += e.Message + " " + e.StackTrace;
}
} // end of SendMail method
} // end of class client
} // end of namespace Ravindra
*****************end of Modified SMTPMail.cs*********
The program is big but quite simple . A class SMTPClient is derived from TcpClient . Hence all protected and public properties of TcpClient are available to SMTPClient class.
Now go directly to SendMail class. In this class i have added several private variables and corresponding properties like smtpserverIP,MailFrom, MailTo etc. These properties are set by smtpMail.aspx program which is given below.
| Property : |
Description |
| Identity |
This is identity of sender e.g. ravindra |
| MailFrom |
Sender's email address e.g. [email protected] |
| MailTo |
Recepient's email address |
| Subject |
Topic of Mail |
| MailData |
mail contents |
| SMTPServerIP |
IP address of SMTP server |
All these inputs are received from smtpMail.aspx file. In SendMail() method of SMTPMail class
an instance of SMTPClient class is created and connection to smtp server is attempted. The blnconnect flag indicates success/failure connection. If connection fails, then an error message is genearated and program Terminates.
On successful connection(i.e. blnconnect is true) , SMTP server's response is analysed for success code "220". If SMTP responds with success code "220", then tha action starts.
All SMTP commands are stored in array SendBuffer[] . All possible sucsess codes from SMTP server are stored in array ResponseCode[]. So commandes from array SendBuffer[] are sent to smtp server one by one and for each command response from smtp server is analysed by comparing smtp server reply code with any of possible success codes in ResponseCode array. If the command executes successfully then only the next command is attempted. If any of commands is unsuccessful, then error message is generated and program terminates immediately.
Compile this smtpmail.cs file and put it into c:/inetpub/wwwroot/bin directory .
Web based front end is given below. SMTPMail.aspx is put into c:\inetpub\wwwroot directory which is configured as default website in IIS.
This page can be viewed in browser by Typing url "http://localhost/SMTPMAil.aspx. The page shows some texboxes to capture input data like SMTP server ip ,sender's email , recepient;s email, subject, Mail Data etc. and a "Send Mail" button.
When user enters data into textboxes and clicks on "send Mail" button , a function btnSend_Click() is called. In this function , an instance SMTPMail() class is created. Please remember that this SMTPMail class() has been defined in SMTPMAIL.cs file. On btnSend_Click() we capure inputs from user and set various properties of smail(an instance of SMTPMail) and call its sendmail() method. If everythis is OK , then a message "Mail Has been sent successfully" is displayed at the top of the page. If any error occurs ., then error message is displayeed at the top.
<%@ Import NameSpace="Ravindra" %>
<HTML>
<HEAD>
<title>SMTP E-Mail Example by Ravindra Sadaphule </title>
<Script language="C#" runat="server">
void btnSend_Click(Object Sender,EventArgs e)
{
if(Page.IsPostBack)
{
SMTPMail smail = new SMTPMail() ; ;
smail.MailFrom = txtfrom.Text ;
smail.MailTo = txtto.Text ;
smail.MailData = txtmessage.Text ;
smail.Subject = txtSubject.Text ;
smail.SMTPServerIP = txtSMTPServerIP.Text ;
smail.SendMail();
if (smail.ErrorMessage!="")
{
Response.Write("Error: " + smail.ErrorMessage) ;
}
else
{
/*
for debugging only.
//Response.Write(smail.ServerResponse + "Mail Sent successfully") ;
*/
Response.Write("<br>Mail Sent successfully<br>") ;
}
}
}
</Script>
</HEAD>
<body>
<form name="frm1" runat="server" ID="Form1">
<table width="100%">
<tr>
<td colspan="2" align="center"><h3>SMTP MAIL
</h3>
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle">SMTP SERVER IP:</td>
<td width="70%" align="left" valign="middle">
<asp:textbox id="txtSMTPServerIP" runat="server" />e.g. 127.0.0.1
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle">
From:
</td>
<td width="70%" align="left" valign="middle">
<asp:textbox id="txtfrom" runat="server" />e.g. [email protected]
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle">
To:
</td>
<td width="70%" align="left" valign="middle">
<asp:textbox id="txtto" runat="server" />e.g. [email protected]
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle">
Sub:
</td>
<td width="50%" align="left" valign="middle">
<asp:textbox id="txtSubject" runat="server" />e.g. Marriage Proposal
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle">
Message:
</td>
<td width="70%" align="left" valign="middle">
<asp:textbox id="txtmessage" TextMode="MultiLine" Rows="5" runat="server" />
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle"> </td>
<td width="70%" align="left" valign="middle">
<asp:button text="Send Mail" id="btnSend" OnClick="btnSend_Click" runat="server" />
</td>
</tr>
<tr>
<td width="30%" align="center" valign="middle"> </td>
<td width="70%" align="left" valign="middle">Developer: <a href="mailto:[email protected]">
Ravindra Sadaphule</a>
</td>
</tr>
</table>
</form>
</body>
</HTML>