java - Must issue a STARTTLS command first -

i running simple example gmail account, not working , giving following error:

      send failed, exception: com.sun.mail.smtp.smtpsendfailedexception: 530 5.7.0 must issue starttls command first. nv2sm4478384pbb.6       

here code

   public class email {    public static void main(string [] args)    {         properties props = new properties();         props.put("mail.smtp.host", "smtp.googlemail.com");         props.put("mail.from", "myemail@gmail.com");           session session = session.getinstance(props, null);          try {             mimemessage msg = new mimemessage(session);             msg.setfrom();             msg.setrecipients(message.recipienttype.to,                               "myemail@hotmail.com");             msg.setsubject("javamail hello world example");             msg.setsentdate(new date());             msg.settext("hello, world!\n");             transport.send(msg);         } catch (messagingexception mex) {             system.out.println("send failed, exception: " + mex);         }    } } 

you attempting use gmail's servers on port 25 deliver mail third party on unauthenticated connection. gmail doesn't let this, because anybody use gmail's servers send mail else. called open relay , common enabler of spam in days. open relays no longer acceptable on internet.

you need ask smtp client connect gmail using authenticated connection, on port 587.