A client I am hosting received an automatic email recently containing:
Please update your site at [domain] to WordPress 5.0.12.
We tried but were unable to update your site automatically.
Obviously, this won't work, and the email should never have been sent.
While WP_CORE_UPDATE is false, this doesn't seem to have stopped the email.
Seems like the best way to disable this is with:
function disable_core_update_emails($notify, $item) {
return false;
}
add_filter('send_core_update_notification_email', 'disable_core_update_emails');
However, that can't go in wp-config.php, as the add_filter() function is not
defined at that point. I'm not sure if there's another location that Debian
patches that could have this defined.