I have problem with send e-mail, if I send one mail is ok no problem, but if
I send mail in loop I have exception,  this is code :

mail.polacz_SMTP(smtpServer);
   while(st.hasMoreTokens())
       {
          String sent_to = st.nextToken();
           mail.send(sent_to, from, subject, body);
       }

podlcza_SMTP :

  private static  String zawartosc_maila=null;
  private static Session session1;

public static void polacz_SMTP(String smtpServer)
{
  try{
   Properties props = System.getProperties();
   boolean debug = false;

    props.put("mail.smtp.host", smtpServer);
     props.put("mail.smtp.auth", "true");
     Authenticator auth = new SMTPAuthenticator();

     session1 = Session.getInstance(props,auth);

     session1.setDebug(debug);

  }catch(Exception ex)
  {
      System.out.print(ex+"\n");
  }
}

Send :

public static void send(String to, String from , String subject, String
body)
 {
   try
   {

     Message msg = new MimeMessage(session1);

     msg.setFrom(new InternetAddress(from));
     msg.setRecipients(Message.RecipientType.TO,
     InternetAddress.parse(to, false));

     msg.setSubject(subject);
     msg.setText(body);

     msg.setHeader("X-Mailer", "LOTONtechEmail");
     msg.setSentDate(new Date());

     Transport.send(msg);
     System.out.println("Message sent OK.");

   }
   catch (Exception ex)
   {
     ex.printStackTrace();
     javax.swing.JOptionPane.showMessageDialog(null,"Blad podczas wysyłania
poczty"+"\n"+ex);
   }
 }

AND DEBUG :

DEBUG: setDebug: JavaMail version 1.4ea
DEBUG: getProvider() returning
javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun
Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "smtp.wp.pl", port 25, isSSL false
554 RBL listed, go away
DEBUG SMTP: could not connect to host "smtp.wp.pl", port: 25, response: 554

maile ida pod jeden adres w petli (20 razy) i jak mowilem czesc sie wysyla :

DEBUG: setDebug: JavaMail version 1.4ea
DEBUG: getProvider() returning
javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun
Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "smtp.wp.pl", port 25, isSSL false
220 smtp.wp.pl ESMTP
DEBUG SMTP: connected to host "smtp.wp.pl", port: 25

EHLO p-4doukpgxp54lk
250-smtp.wp.pl
250-PIPELINING
250-AUTH=LOGIN PLAIN
250-AUTH LOGIN PLAIN
250-STARTTLS
250-SIZE
250-X-RCPTLIMIT 100
250 8BITMIME
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "AUTH=LOGIN", arg "PLAIN"
DEBUG SMTP: Found extension "AUTH", arg "LOGIN PLAIN"
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "SIZE", arg ""
DEBUG SMTP: Found extension "X-RCPTLIMIT", arg "100"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Attempt to authenticate
AUTH LOGIN
334 VXNlcm5hbWU6
a3VsZWp0b21hc3o=
334 UGFzc3dvcmQ6
bGVvbmNhcnMx
235 go ahead
DEBUG SMTP: use8bit false
MAIL FROM:<kulejtomasz@wp.pl>
250 ok
RCPT TO:<tomaszkulej@o2.pl>
250 ok
DEBUG SMTP: Verified Addresses
DEBUG SMTP:   tomaszkulej@o2.pl
DATA
354 Please start mail input.
Date: Wed, 30 Aug 2006 18:17:08 +0200 (CEST)
From: kulejtomasz@wp.pl
To: tomaszkulej@o2.pl
Message-ID: <21151438.01156954628546.JavaMail.tkulej@p-4doukpgxp54lk>
Subject: 20
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Mailer: LOTONtechEmail

t
.
250 Mail queued for delivery.
QUIT
221 Closing connection. Good bye.
Message sent OK.