WP Cron with wp_schedule_event()

wp_cron_sample.php

<?php

/**
 * Register the cron on plugin loaded.
 * Valid values for the recurrence are ‘hourly’, ‘daily’, and ‘twicedaily’.
 * @return void
 */
function harisrozak_register_wp_cron() {
    if ( ! wp_next_scheduled( 'harisrozak_wp_cron' ) ) {
        wp_schedule_event( time(), 'twicedaily', 'harisrozak_wp_cron' );
    }
}
add_action( 'plugins_loaded', 'harisrozak_register_wp_cron', 1401 );

/**
 * Unregister the cron on plugin deactivation.
 * @return void
 */
function harisrozak_unregister_wp_cron() {
    wp_clear_scheduled_hook( 'harisrozak_wp_cron' );
}
register_deactivation_hook( HARISROZAK_PLUGIN_FILE, 'harisrozak_unregister_wp_cron' );

/**
 * The cron function to run periodically.
 * @return void
 */
function harisrozak_wp_cron_function() {
	wp_mail( '[email protected]', 'Automatic email', 'Automatic scheduled email from WordPress.');
}
add_action( 'harisrozak_wp_cron', 'harisrozak_wp_cron_function', 10 );