Laravel Mail::failures() method is not working

The failures() method is not working. It returns an empty array while sending an invalid email.

Mail::send('mail_templates', $messageData, 
    function ($message) use ($firstname, $email_id) {
        $message->to($email_id, $firstname)
            ->subject('Welcome Mail');
});

$a = Mail::failures();

return $a;

I checked the from email address.

Address not found

The notification occurred in FROM EMAIL and the mail failure response shows an empty array ([]). I want to know if the email is sent or not while the API calls to mail send process in Laravel.