Disable WordPress update email notifications

functions.php

<?php

// place the code below into the functions.php file from your WordPress child theme

// disable core update notifications
add_filter( 'auto_core_update_send_email', 'fws_stop_auto_update_emails', 10, 4 );
function fws_stop_update_emails( $send, $type, $core_update, $result ) {
  if ( ! empty( $type ) && $type == 'success' ) {
    return false;
  }
  return true;
}

// disable plugin update notifications
add_filter( 'auto_plugin_update_send_email', '__return_false' );

// disable theme update notifications
add_filter( 'auto_theme_update_send_email', '__return_false' );