java批量电子邮件发件人

Question

I need to design an application in java which can send like 200-300 mails/sec. How to get it done. I tried the simple Transport.send() which sends one mail at a time but that takes around 2-3 secs in itself. Also will google smtp allow me to send this much number of mails per second ?! How to implement something like batch mail sending or can something like multi-threading help?

Answer 1

Transport.send() is not an efficient way to send mass mails as it will open fresh connection for each message. Average time taken for each message is around 4 seconds.

Try below code:

Session session = Session.getDefaultInstance(props,new javax.mail.Authenticator() {  
        protected PasswordAuthentication getPasswordAuthentication() {  
            return new PasswordAuthentication("FROM","PASSWORD");  
        }  
    });
Transport transport = session.getTransport("smtp");
transport.connect();
try{
   for(Message m : messages) {
   transport.sendMessage(m, m.getAllRecipients()); // time decreased to 2 second/message
   }
}finally {
t.close();
}

Further you can try implementing using ThreadPool having fixed number of Thread depending upon the system you are having.

Answer 2

Yes, you need a multithreaded server. As you wrote, you will use about 1000 threads for sending, that is feasible on any hardware from a CPU performance viewpoint, but you have to have adequate memory too.