if (!wp_next_scheduled('my_task_hook')) {
	wp_schedule_event( time(), 'hourly', 'my_task_hook' );
}

add_action( 'my_task_hook', 'my_task_function' ); 

function my_task_function() {
	wp_mail('[email protected]', 'Automatic email', 'Hello, this is an automatically scheduled email from WordPress.');
}

scheduled event in Wordpress

wordpress

PHP