Add to mu-plugins folder, auto add every new user to a sendy list. Works with default WordPress and Woocommerce registrations.

sendy.php

<?php
add_action( 'user_register', 'add_user_to_sendy_list' );

function add_user_to_sendy_list( $user_id ) {
  $list = 'SENDY_LIST_ID';
  $url  = 'http://SENDY_INSTALL_URL/subscribe';
  $user = get_userdata( $user_id );
  
  $email = $user->data->user_email;
  $name  = $user->data->user_nicename;
  
  $args = array(
    'body' => array(
      'email' => $email,
      'name'  => $name,
      'boolean' => true,
      'list'    => $list
    )
  );
  
  $result = wp_remote_post( $url, $args );
}

This is great, thank you!
However, I was wondering if you might have any idea on how to make it unsubscribe a user from the same Sendy mailing list, when deleting that user from the WP users? So basically, adding the reverse of what it does now.

Thank you very much!

Great work, can we use it ONLY if the user has verified email upon registration in WordPress? I don't want to send an invalidated email to sendy to avoid SES health issues..