Cannot catch invalid email addresses

Question

Hi,
I have been using this very normal email sending routine but for some reason even if the email address is invalid (ex abc), the Transport.send() method does not throw any exception and continues.
Does anyone know why this should happen??
The code is given below
     for (int i = 0; i < p.length; i++){
uEmail = p.getUserEmail();
System.out.println("Sending Email to :" + uEmail);
     emailContent = emailString;
/***************** SENDING THE EMAILS *************************/
try {
          Properties props = System.getProperties();
//System.out.println("Using mail server"+mailserveraddress);
          props.put("mail.smtp.host",mailserveraddress);
          Session session = Session.getDefaultInstance(props, null);
Message message = new MimeMessage(session);
message.setFrom(new InternetAddress("[email protected]"));
message.addRecipient(Message.RecipientType.TO, new InternetAddress(uEmail));
message.setSubject("Homeland Headlines " + dateString);
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setText(emailContent);
Multipart multipart = new MimeMultipart();
multipart.addBodyPart(messageBodyPart);
//System.out.println("Setting the content");
message.setContent(multipart);
          //System.out.println("NO exception till here");
// Send the message
Transport.send(message);
          System.out.println("Email Sent successfully");
catch(SendFailedException me) {
          System.out.println("Email not sent to :" + uEmail);
          System.out.println("The exception is" +me.toString());
          invalidemails.add(uEmail);
          catch(MessagingException mesex){
          System.out.println("The exception is:"+mesex.toString());
          sentemailflag="false";
          catch(Exception e){
               System.out.println("Unexpected error is:"+ e.toString());
               sentemailflag="false";
The control never reaches any of the exception blocks even though p has some invalid email addresses.
It prints:
Sending email to: abc
Email sent successfully
Thanks,
Chetan

Answer 1

Hi,
I believe I have answered this question quite a few times in this forum.
There is no standard way to know if the e-mail id exists or not, SMTP standards does not mandate the server implementors to notify this.
There are several things that can happen:
a. The server implements the VRFY command -- Then you know immediately if the account is active.
b. The server does not implement the VRFY command, but if the acount does not exist tells you when you send the RCPT command.
c. The server does not tell you till you say QUIT.
d. The server accepts the mail silently and sends a mail later saying that the mailbox does not exist.
Since there is no sure-shot way of determining this no exception is thrown.
(Also check out the RFC for a typical SMTP session if the commands confuse you.)
cheers
Projyal