email - Spring MVC bulk message using MimeMessagePreparator -

i'm trying send bulk emails using spring mvc. here code:

    if(customerclients != null){          int count = 0;         boolean sent = false;          list<mimemessagepreparator> preparators = new arraylist<mimemessagepreparator>();          (bulkemail client : customerclients) {              if(customerid==-1)                 customerid = client.getcustomerid();              customeraccount customeraccount = service.getcustomeraccount(client.getcustomerid());              if (instantmessage.isemailchecked() && customeraccount.getbalance()>0) {                  try{                     final string receiverid = client.getemail();                     instantmessage.setipersonorgroupvalue(receiverid);                       preparators.add(new mimemessagepreparator()                          {                             public void prepare(mimemessage mimemessage) throws exception                              {                                 final mimemessagehelper message = new mimemessagehelper(mimemessage, true, "utf-8");                                 message.setsubject(instantmessage.getsubject());                                 message.setto(receiverid);                                 message.setfrom(from);                                  message.settext(instantmessage.getmessage(), true);                             }                         });                       sent = false;                 }                 catch(exception ex){                     ex.printstacktrace();                 }             }              ++count;              if(count%100==0){                 springmail.send(preparators);                 preparators = new arraylist<mimemessagepreparator>();                 sent = true;             }         }          if(!sent)             springmail.send(preparators); 

here code uses javamailsender sending preparators:

public void send(list<mimemessagepreparator> preparatorslist) {     mimemessagepreparator[] preparators = preparatorslist.toarray(new mimemessagepreparator[preparatorslist.size()]);     mailsender.send(preparators);        } 

the problem code takes around 1 second per email address. means 300 emails in 5 minutes. want know if normal or there can improve.

thanks