I want to send all unread emails from server to another email address.

I send each unread email using HostGator.

After sending 30-40 mails an error occurs.

Could not connect to SMTP host, nested exception is: java.net.ConnectException: Connection refused: connect

I checked with smtp port 25, 465, 587. Same error appears.

Email send method:

public static void send(String sub,final String user, final String pass, String toMails) throws Exception {   
    Properties props = new Properties();
    props.put("mail.smtp.host", "gator.hostgator.com");
    props.put("mail.smtp.port", "25");
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "true");
  
    Session session = Session.getInstance(props, new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(user, pass);
        }
    });
    MimeMessage message = new MimeMessage(session);
    message.setFrom(new InternetAddress(user));
    message.addRecipients(Message.RecipientType.TO, toMails);

    message.setSubject(sub);
    message.setText("-Body-");
   
    BodyPart messageBodyPart1 = new MimeBodyPart();
    messageBodyPart1.setText("-Body-");      

    Multipart multipart = new MimeMultipart();
    multipart.addBodyPart(messageBodyPart1);    
    message.setContent(multipart);  
    Transport.send(message);
}

This is error message: