Laravel 9 sending email notifications error "An email must have a "To", "Cc", or "Bcc" header."

Question

I am trying to send a notification to a set of users. According to the Laravel documentation I should be able to send notifications as follows:

Notification::send($users, new ConsumableNotification($arguments));

as long as the $users is a collection or array of notifiable objects. However I am facing this error:

   Symfony\Component\Mime\Exception\LogicException 

  An email must have a "To", "Cc", or "Bcc" header.

I have tried sending notifications to the individual users as follows

foreach ($users as $user) {
    $user->notify(new ConsumableNotification($arguments));
}

With the same error occurring. However sending a mail explicitly:

foreach ($users as $user) {
    Mail::to($user)
        ->send(new ConsumableAlert($arguments));
}

works, so I assume something goes wrong in the notification class. The notification class is defined as follows:

class ConsumableNotification extends Notification
{
    use Queueable;

    /**
     * Create a new notification instance.
     *
     * @return void
     */
    public function __construct(
        public ConsumableTypes $consumableType,
        public float|null $remains = null,
        public Carbon|null $expires = null,
    )
    {
        //
    }

    /**
     * Get the notification's delivery channels.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function via($notifiable)
    {
        return ['mail', 'database'];
    }

    /**
     * Get the mail representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return \Illuminate\Notifications\Messages\MailMessage
     */
    public function toMail($notifiable)
    {
        return (new ConsumableAlert(
            $this->consumableType,
            $this->remains,
            $this->expires
        ));
    }

    /**
     * Get the array representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function toArray($notifiable)
    {
        return [
            'consumable_type_id' => $this->consumableType->id,
            'remains' => $this->remains,
            'expires' => $this->expires
        ];
    }
}

Does anyone spot the issue?

Answer 1

After spending way to much time I saw that one is required to add the to method in the notification class like this:

/**
 * Get the mail representation of the notification.
 *
 * @param  mixed  $notifiable
 * @return \Illuminate\Mail\Mailable
 */
public function toMail($notifiable)
{
    return (new MyMailable($arguments))
        ->to($notifiable->email);
}

Somehow I missed it 5 times when reading the documentation.