Unable to send simple email

Hi, I’m trying to send a simple email upon user registration. It seems that I’m following the documentation correctly, yet I do not receive the email.

use Cake\Mailer\Email;

class UsersController extends AppController


public function register(){
    $user = $this->Users->newEntity();
        $user = $this->Users->patchEntity($user, $this->request->getData());
            $this->Flash->success('You are registered and can login');

            // Send email
            $email = new Email('default');
            $email->setFrom(['testAdmin@xtra.co.nz' => 'Bargin Books'])
                ->send('Welcome to Bargin Books');

            return $this->redirect(['action' => 'login']);
            $this->Flash->error('You are not registered');
    $this->set(compact('user')); //users?
    $this->set('_serialzie', ['user']);


I appreciate your help

Oh well, it works with an @gmail.com account, though not an @xtra.co.nz account.

Are you using the Mail transport, or SMTP? If the latter, what server are you sending through? This seems very much like a restriction outside of Cake.