Send mail via SMTP

SmtpMailer.java

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.*;

/**
 * SmtpMailer is used to send mail using SMTP.
 *
 * @author  Thornton Rose
 * @version 1.0
 */
public class SmtpMailer {
   // Fields

   private static final int  SMTP_PORT = 25;
   private static final char SMTP_ERROR_CODE1 = '4';
   private static final char SMTP_ERROR_CODE2 = '5';
   
   protected boolean trace = false;

   // Methods
   
   /**
    * main() provides a way to test this class from the command line.
    *
    */
   public static void main(String[] args) {
      SmtpMailer mailer;
      String status;
      
      if (args.length != 7) {
         System.out.println("Usage: SmtpMailer <host> <domain> <sender> <recipients> <content-type> <subject> <text>");
      } else {
         mailer = new SmtpMailer();
         mailer.trace = true;
         status = mailer.send(args[0], args[1], args[2], args[3], args[4], args[5], args[6]);

         System.out.println("\nStatus: " + status);
      }
   }

   /**
    * send() sends the mail.
    *
    * @param host          Host name or IP.
    * @param domain        Sender's domain.
    * @param sender        Sender's address.
    * @param recipients    Recipient addresses.
    * @param contentType   MIME type for mail.
    * @param subject       Subject line.
    * @param maildata      Mail data.
    *
    * @return Status message, which will be "OK" if successful.
    */
   public String send(
      String host,
      String domain,
      String sender,
      String recipients,
      String contentType,
      String subject,
      String mailtext) {

      Socket            mailSocket;
      BufferedReader    socketIn;
      DataOutputStream  socketOut;
      String            address;
      StringTokenizer   tokenizer;
      String            maildata = "";
      String            result = "OK";
      Date              mailDate = new Date();
      String            formattedMailDate;
      SimpleDateFormat  dateFormatter;

      // Set the content type.
      
      if (! contentType.equals("")) {
         maildata = maildata + "Content-type: " + contentType + "\n";
      }
      
      // Build the mail date.
      //
      // Example: Fri, 2 Jul 1999 12:49:01 PDT

      dateFormatter = new SimpleDateFormat("EEE, d MMM yyyy HH:mm zzz");
      formattedMailDate = dateFormatter.format(mailDate);

      // Add the date and the rest of the fields.

      maildata = maildata + 
         "Date: " + formattedMailDate + "\r\n" + 
         "From: " + sender + "\r\n" +
         "To: " + recipients + "\r\n" +
         "Subject: " + subject + "\r\n" +
         "\r\n" +
         mailtext + "\r\n";

      try {
         // Open the connection to the SMTP server.

         mailSocket = new Socket(host, SMTP_PORT);
         
         try {

            // Get the input and output streams.
         
            socketIn = new BufferedReader(
               new InputStreamReader(mailSocket.getInputStream()) );
            socketOut = new DataOutputStream(mailSocket.getOutputStream());

            // Get the initial reply from the server.

            readReply(socketIn);

            // Greet the server.

            sendCommand(socketOut, "HELO " + domain);
            readReply(socketIn);

            // Send the sender's address.
      
            sendCommand(socketOut, "MAIL FROM: " + sender);
            readReply(socketIn);

            // Send the list of recipients.

            tokenizer = new StringTokenizer(recipients, ",");

            while (tokenizer.hasMoreElements()) {
               sendCommand(socketOut, "RCPT TO: " + tokenizer.nextToken());
               readReply(socketIn);
            }

            // Start the data section.

            sendCommand(socketOut, "DATA");
            readReply(socketIn);

            // Send the mail message.
      
            sendCommand(socketOut, maildata + ".");
            readReply(socketIn);

            // End the session.
      
            sendCommand(socketOut, "QUIT");
            readReply(socketIn);

         } finally {
            mailSocket.close();
         }

      } catch(Exception theException) {
         result = theException.toString();
      }
      
      return result;
   }

   /**
    * sendCommand() sends an SMTP command to the SMTP server. An
    * SMTP command is a string that look like:
    * <pre>
    * [key words] [data][CR][LF]
    * </pre>
    *
    * <p>Example: <pre>HELO xyz.com</pre>
    *
    * @param out      The output stream to which to write the command.
    * @param command  The command to write.
    *
    * @exception IOException No special handling is done; the exception is
    *    passed back up the call chain.
    */
   private void sendCommand(DataOutputStream out, String command) 
      throws IOException {
      
      out.writeBytes(command + "\r\n");
      
      if (trace) {
         System.out.println(command);
      }
   }

   /**
    * readReply() reads the reply from the SMTP server.
    *
    * @param reader  The input reader from which to read the reply.
    *
    * @exception IOException If an IOException occurs because of an error
    *    with socket IO, no special handling is done, and the exception is
    *    passed back up the call chain. If the status code in the reply from
    *    the SMTP server is equal to SMTP_ERROR_CODE1 or SMTP_ERROR_CODE2, an
    *    IOException containing "SMTP: <reply>" is thrown.
    */
   private void readReply(BufferedReader reader)
      throws IOException {
      
      String reply;
      char   statusCode;
      
      reply = reader.readLine();
      statusCode = reply.charAt(0);
      
      if (trace) {
         System.out.println(reply);
      }

      if ( (statusCode == SMTP_ERROR_CODE1) | 
           (statusCode == SMTP_ERROR_CODE2) ) {
         throw (new IOException("SMTP: " + reply));
      }
   }
   
} // end SmtpMailer