Заглушка писем Bitrix24

init.php

<?
/*
* Add to /local/php_interface/init.php
*/

use Bitrix\Main\Diag\Debug;

function custom_mail($to, $subject, $message, $additional_headers, $additional_parameters) {

    $fields = array(
        'datetime' => date('d.m.Y H:i:s'),
        'to' => $to,
        'subject' => $subject,
        'message' => $message,
    );

    Debug::writeToFile($fields, '', 'CUSTOM_MAIL_DEBUG.log');
}