Mail Change Timing

By default, wp-cron-mail executes roughly every fifteen minutes. If you’d like to change this to run roughly once per hour, change line 14 from: add_action(‘wp_cron_15’, ‘wp_cron_mail’); to add_action(‘wp_cron_hourly’, ‘wp_cron_mail’);
If you only want once per day, change hourly to daily in the line above.