firefly-iii/app/Http/Controllers/CronController.php

<?php

namespace FireflyIII\Http\Controllers;

use FireflyIII\User;

/**
 * Class WebhookController
 *
 * @package FireflyIII\Http\Controllers
 */
class CronController extends Controller
{

    /**
     * Firefly doesn't have anything that should be in the a cron job, except maybe this one, and it's fairly exceptional.
     *
     * If you use SendGrid like I do, you can detect bounces and thereby check if users gave an invalid address. If they did,
     * it's easy to block them and change their password. Optionally, you could notify yourself about it and send them a message.
     *
     * But thats something not supported right now.
     */
    public function sendgrid()
    {

        if (strlen(env('SENDGRID_USERNAME')) > 0 && strlen(env('SENDGRID_PASSWORD')) > 0) {

            $set = [
                'blocks'   => 'https://api.sendgrid.com/api/blocks.get.json',
                'bounces'  => 'https://api.sendgrid.com/api/bounces.get.json',
                'invalids' => 'https://api.sendgrid.com/api/invalidemails.get.json',

            ];
            echo '<pre>';
            foreach ($set as $name => $URL) {


                $parameters = [
                    'api_user' => env('SENDGRID_USERNAME'),
                    'api_key'  => env('SENDGRID_PASSWORD'),
                    'date'     => 1,
                    'days'     => 7
                ];
                $fullURL    = $URL . '?' . http_build_query($parameters);
                $data       = json_decode(file_get_contents($fullURL));

                /*
                 * Loop the result, if any.
                 */
                if (is_array($data)) {
                    echo 'Found ' . count($data) . ' entries in the SendGrid ' . $name . ' list.' . "\n";
                    foreach ($data as $entry) {
                        $address = $entry->email;
                        $user    = User::where('email', $address)->where('blocked', 0)->first();
                        if (!is_null($user)) {
                            echo 'Found a user: ' . $address . ', who is now blocked.' . "\n";
                            $user->blocked      = 1;
                            $user->blocked_code = 'bounced';
                            $user->password     = 'bounced';
                            $user->save();
                        } else {
                            echo 'Found no user: ' . $address . ', did nothing.' . "\n";
                        }
                    }
                }
            }
            echo 'Done!' . "\n";
        } else {
            echo 'Please fill in SendGrid details.';
        }

    }

}