When a packing slip (also known as an advance shipping notice (ASN)) is created and posted for a sales order, it is added to the Packing slip journal. If an applicable document flow with direction 'Outbound' and type 'Advance ship notice' exists, also a record is added to the Outbound message queue. When this record is processed, the 'Sales - Delivery to XML' message is run. As a result, an EDI sales ASN message file is created and is sent to your customer.