Following the introduction in 1999 of an electronic archive for the audit-proof retention of invoices to relieve the burden on the paper archive, in 2005 the German travel agency DER wanted to optimise its invoice processing. Prior to automation, invoices without a purchase order reference went around the company with the rest of the internal post before being approved and entered in the SAP system manually. Tourism invoices with a purchase order reference were sent by freight to Galway in Ireland, where they were entered in SAP manually. Clarification processes were laborious and based on email or internal post.