Send mail from GCLOUD to other email(gmail,yahoo). Like email verification link, subscription confirmation

Question

     import java.util.*;  
import javax.mail.*;  
import javax.mail.internet.*;  
import javax.activation.*;  

public class SendEmail  
{  
 public static void main(String [] args){  
      String to = "[email protected]";

      String from = "[email protected]";
      String host = "localhost";//or IP address  


      Properties properties = System.getProperties();  
      properties.setProperty("mail.smtp.host", host);  


      Session session = Session.getDefaultInstance(properties);  

      try{  
         MimeMessage message = new MimeMessage(session);  
         message.setFrom(new InternetAddress(from));  
         message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));  
         message.setSubject("Ping");  
         message.setText("Hello, this is example of sending email  ");  

         // Send message  
         Transport.send(message);  
         System.out.println("message sent successfully....");  

      }catch (MessagingException mex) {mex.printStackTrace();}  
   }  
}  

I dont want to go for sendgrid/google-email-api/mailgun I have mapped DNS-A(host) @ 23.236.49.96 600 seconds sharenodes.com But not able to send mail. Tried properties.put("mail.smtp.port", "2525"); But no mail received neither error. For port 25, 465, 587 it throws error as google has blocked these ports

Answer 1

Google Compute Engine does not allow outbound connections on ports 25, 465, and 587. With that said, you can set up your own email server on any of the ports not blocked by Compute Engine or you can use partner services like SendGrid, Mailgun, or using Google Apps. The information is documented on this link