Disable auto update notices - add code snippet.

disable-auto-update-notices.php

// Dissable core auto update notices if sucessful.
add_filter( 'auto_core_update_send_email', 'capweb_stop_auto_update_emails', 10, 4 );
function capweb_stop_update_emails( $send, $type, $core_update, $result ) {
if ( ! empty( $type ) && $type == 'success' ) {
	return false;
}
return true;
}
// Dissable theme and plugin auto update notices.
add_filter( 'auto_plugin_update_send_email', '__return_false' );
add_filter( 'auto_theme_update_send_email', '__return_false' );