Connect to SMTP following a connection failure

Question

If I try to send a mail when I do not have an internet connection I get the "Unknown SMTP" type exception as expected. If I then connect to the internet and try to send again then I still always get the same exception. If I restart my app then sending is again no problem.
I have tried creating a new session instance (and not using the default one) and re-connecting via the Transport but it doesn't help.
When I first ask to connect with the internet connection missing I have to wait about 60 seconds until it gives up. When I try to connect again the exception appears immediately without any wait - so something is obviously different. Is there some static setup in JavaMail that is not being cleared down for a new Session/Transport?
Interestingly this problem happens on a computer (MacOSX) that is connected to the internet via another computer(Win2000) on a LAN. It doesn't happen on the computer that is connected directly to the internet.
Can anybody offer any advice here, I can't expect my users to restart the application because they didn't have a connection when they first tried to send.
Thanks
John

Answer 1

When are you creating your session object? Are you creating a new one for every attempt at sending or are you creating it when the application starts?
It looks like the problem is the application takes a snap shot of the system when it starts and has no idea about the internet connection that gets established afterwards.
Take a look at the following code. This is an email class that I am using off of several JSP pages to enable web email forms. It recreates the session each time it is called.
import java.util.*;
import java.util.Properties;
import java.net.*;
import java.io.*;
import java.lang.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
import javax.activation.FileDataSource;
import javax.activation.DataHandler;
import java.rmi.server.UID;
public class EmailSendMessage303
     public String sendmessage(String toField, String subjectField, String messageText, String myAddress, String attachmentFile)
          OutputStream errorOS;
          String outString = "";
          String uidString = "";
          try
               Properties props = System.getProperties();
               props.put("mail.smtp.host","Your server");
               props.put("mail.transport.protocol","smtp");
               props.put("mail.server","Your Server");
               Session session = Session.getDefaultInstance(props,null);
               Message msg = new MimeMessage(session);
               StringTokenizer toST = new StringTokenizer(toField,",");
               if (toST.countTokens() > 1)
                    InternetAddress[] address = new InternetAddress[toST.countTokens()];
                    int addrIndex = 0;
                    String addrString = "";
                    while (toST.hasMoreTokens())
                         addrString = toST.nextToken();
                         address[addrIndex] = (new InternetAddress(addrString));
                         addrIndex = addrIndex + 1;
                    msg.setRecipients(Message.RecipientType.TO, address);
               else
                    InternetAddress[] address = {new InternetAddress(toField)};
                    msg.setRecipients(Message.RecipientType.TO, address);
               InternetAddress from = new InternetAddress(myAddress);
               msg.setFrom(from);
               msg.setSubject(subjectField);
               UID msgUID = new UID();               
               uidString = msgUID.toString();
               msg.setHeader("X-Mailer",uidString);
               msg.setSentDate(new Date());
               MimeMultipart mp = new MimeMultipart();
               // create body part for textarea
               MimeBodyPart mbp1 = new MimeBodyPart();
               mbp1.setContent(messageText,"text/plain");
               mp.addBodyPart(mbp1);
               msg.setContent(mp);
               try {
                    Transport.send(msg);
               } catch (SendFailedException sfe)
                    return sfe.toString();
          catch (Exception eq)
               return eq.toString();
          return ("SENT:" + uidString);
}