Why do we recommend Jetpack's Monitor
If you enable Scheduled emails in ProjectHuddle, we recommend you use Jetpack's Downtime Monitoring module to ensure they deliver on time. Without something like this enabled, it's possible to miss scheduled email times if there are no active visitors on your site.
This is because WordPress' cron relies on active visits to the site. Jetpack's Downtime Monitoring solves this by pinging your site every 5 minutes. This ensures your scheduled jobs run accurately, with the added benefit of notifying you of potential downtime.
In short, we recommend this because it's easy to implement, free, and gives you an added bonus of downtime monitoring.
Free Alternatives
If you prefer not to use Jetpack you there are other options!
1. Use UptimeRobot for free
You can configure this free service to ping your site at http://yoursite.com/wp-cron.php.
2. Have your host enable a real Cron
This involves first turning off WordPress' cron in your wp-config.php file
define('DISABLE_WP_CRON', true);
Then setting up a cron to ping your wp-cron.php file on your server, every 5 minutes:
*/5 * * * * php /var/www/vhosts/mysite/web/wp-cron.php
Many times your host will be able to do this for you!