Hi,I have this problem since otrs 4.x, and it is still here, but I don't know if it is something in my configuration.here is the problem: when you create a new external email, if you add a customer user via the Address Book, it writes the address as "Customer Name" <customer@email customer_id>.As you can see, there is the "customer_id" inside the <>, with the result that the email is sent to customer@emailcustomer_id which is nonexistant and bounces back.I never understood why this happens.--Lynx International SrlStefano FinettiLynx International Srl is a part of AXED GroupVia Pier Luigi Nervi e/3 - Torre 6 - 04100 Latina