athenahr/app/Http/Requests/InvitationRequest.php

<?php

namespace App\Http\Requests;

use App\Facades\Options;
use Illuminate\Auth\Access\AuthorizationException;
use Illuminate\Foundation\Http\FormRequest;

class InvitationRequest extends FormRequest
{
    public function rules(): array
    {
        return [
            'email' => ['required', 'email', 'max:254'],
        ];
    }

    public function authorize(): bool
    {
        return !Options::getOption('enable_registrations');
    }

    protected function failedAuthorization()
    {
        throw new AuthorizationException(__('You cannot request a new invite for this user/e-mail address right now. Keep in mind that users can only be invited once.'));
    }
}