Use Laravel routeNotifcationForMail() to send to multiple emails addresses?

I'm using the Notifiable trait on my Model.

I have a de-normalised list of subscribed emails. i.e a comma separated string.

The documentation and my background reading suggests that this will only route to a single email address.

<?php

namespace App;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;

class User extends Authenticatable
{
    use Notifiable;

    /**
     * Route notifications for the mail channel.
     *
     * @return string
     */
    public function routeNotificationForMail()
    {
        return $this->email_address;
    }
}

Laravel 5.3 Notifications

I've also read Matt Stauffer on Notifications but can't see an answer there.

via Chebli Mohamed