Hi teashop ,
Please note that custom development is out of the scope of our support.
Anyway, adding a snippet like the next should work.
add_filter( 'woocommerce_email_recipient_mi_notify_expired_inventory', function() {
return 'person1@gmail.com';
});
Please note that this is an example code provided as it is and may not work. If you don't know how to add or modify it, I kindly suggest finding a developer to help you.
Best Regards,
José Andrés