I already have a program to send the email using JavaAPI.
The catch is that if let's say if firstname.lastname@example.org is an invalid email address, it still sends the mail out, and there's no way for my application to
detect that it is a invalid email address.
Assuming that the rebound email received in the email server in 5 sec, I would like to get some reply from the email server, saying that the email
was not sent successfully.