Email notification on post publish

Hey,

I’m trying to setup a simple notification to the author when a post is published.
It works, however, if i try to include any custom fields in the message, i don’t get the meta value for any field, only “1”.


function email_user($post_ID) {
global $wpdb, $post;

$auth = get_post($post_ID);
$auth_PID = $auth->ID;
$authid = $auth->post_author;
$participante_ID = get_post_meta($auth_PID, "nome", true);
$posttype = $auth->post_type;

$to = get_the_author_meta('user_email',$authid);

$headers = 'Example <[email protected]>' . "\r\n" ;
$message= "
Hi, ". $participante_ID[0] ."

Your post is online.

Edit: https://www.example.com/wp-admin/post.php?post=$post_ID&action=edit
Preview: https://www.example.com/?p=$post_ID&preview=true \r\n

Thanks.
";

wp_mail($to, "Post Notification", $message, $headers);
return $post_ID;
}

add_action('publish_participante', 'email_user');

Am I missing something? Thanks a lot,