Glad that you managed to resolve it, with regards to wp_mail it should be semi-straight forward
// Updates FYI last update timestamp when custom field is updated
function my_acf_save_post( $post_id ) {
// bail out early if we don't need to update the date
if( is_admin() || $post_id == 'new' ) {
return;
}
global $wpdb;
$datetime = date("F j, Y g:i a");
$query = "UPDATE $wpdb->posts
SET
post_modified = '$datetime'
WHERE
ID = '$post_id'";
$wpdb->query( $query );
$to = '[email protected]';
$subject = 'Update to ' . get_the_title($post_id);
$message = "There has been an update to your post " . $get_the_title($post_id) . "/n You can click to see this here:" . get_permalink($post_id);
wp_mail($to, $subject, $message);
}
// run after ACF saves the $_POST['acf'] data
add_action('acf/save_post', 'my_acf_save_post', 20);
This is untested mind, but it seems like it would work. Through using wp_mail() to send, it should follow standard site sending protocol (i.e. if you have an SMTP plugin or however your site sends by default).
