Email Digests includes a smart sending mechanism that will perform email sending and this is posible thanks to the WordPress built-in feature Cron.
WordPress Cron basically execute tasks in background periodically (hourly, daily, etc).
By default this feature is enabled on your WordPress install since WordPress uses it to perform some cleanups, scheduled posts and performance checks.
Email Digests makes use of this awesome feature to smartly send emails to all users of your website to avoid any performance issues.
Troubleshooting email sending
If emails created by Email Digests are not being sent there could be many points to check:
1 – Check the email setup of your WordPress (this could by configured by your hosting or through a plugin like SMTP Email or Gmail Oauth Email).
2 – Check if a plugin or your hosting has disabled the WordPress Cron.
3 – Check if in your
wp-config.php you have defined the DISABLE_WP_CRON (if yes, remove this line).
Alternative solution, use alternative Cron
If you are not able to get your Cron working (for example, for limitations from your hosting provider). WordPress includes an alternative cron to let you get cron running on your website.
To activate the alternative cron, go to your
wp-config.php and place the next line at the bottom:
define( 'ALTERNATE_WP_CRON', true );