The increasing automation of business processes is one of the main benefits of the ongoing technological evolution. Regarding e-invoices this automation process is still not optimally supported despite the fact that recent studies indicate a high potential to save costs. Within this paper we identify the main obstacles and propose a multi-stage solution. Therein we classify the e-invoicing process using common security objectives and, since the process includes many security related elements, propose an initial solution based on security patterns. The approach takes advantage of the main benefits of security patterns to provide a domain-independent solution which is built upon expert knowledge.