Send an email when an original post with translations is updated

wpml-notify-on-post-updates.php

<?php
/*
Plugin Name: WPML Notify on Post Updates
Plugin URI: http://wpml.org
Description: Sends an email when an original post with translations is updated.
Version: 0.0.1
Author: Andrea Sciamanna
Author URI: https://www.onthegosystems.com/team/andrea-sciamanna/
*/

// don't load directly
if ( ! defined( 'ABSPATH' ) ) {
	die( '-1' );
}

/**
 * @param int $post_ID
 */
function wpml_notify_on_post_update( $post_ID ) {
	// Skip if it's a REST request (or it will send the same email twice)
	if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
		return;
	}

	$getPostsToUpdate = WPML\FP\pipe(
		WPML\Element\API\PostTranslations::getIfOriginal(),
		WPML\FP\Fns::reject( WPML\FP\Obj::prop( 'original' ) ),
		WPML\FP\Fns::map( WPML\FP\Obj::prop( 'element_id' ) )
	);

	// The current post is not the original or has no translations
	if ( ! $getPostsToUpdate( $post_ID ) ) {
		return;
	}

	// Just a helper function to build anchor tags
	$getLink = function ( $url, $text ) {
		$link_template = '<a href="%1$s" title="%2$s">%2$s</a>';

		return sprintf( $link_template, $url, $text );
	};

	$post = get_post( $post_ID );

	$recipient = get_user_by( 'email', get_option( 'admin_email' ) );

	$subject = 'Translations of ' . $post->post_title . ' may need to be updated';

	$message = [
		'Hello, ' . $recipient->display_name,
		'',
		'<strong>'. $getLink( get_post_permalink( $post_ID ), $post->post_title ) . '</strong> has been modified and its translations may require an update.',
		'',
		$getLink( get_bloginfo( 'url' ), get_bloginfo( 'name' ) ),
	];

	$headers = [ 'Content-Type: text/html; charset=UTF-8' ];

	wp_mail( $recipient->user_email, $subject, implode( '<br>', $message ), $headers );
}

add_action( 'post_updated', 'wpml_notify_on_post_update', 10, 2 );

Download the snippet and save it in your wp-content/plugins.

In WordPress, go to Plugins and activate WPML Notify on Post Updates.

This plugin hooks to post_updated which will trigger every time a post is updated.
Then it will check if that post is marked as "original" and if it has any translation.

If all the conditions are met, it will send an email to the user set as admin of the site.