Original sentence: In 2008 the company issued 20 Rudolph Hess stamps after Neo-Nazis used Deutsche Posts Plusbrief Individuell, a "design-your-own" stamp service which delivers pre-franked, personalised envelopes.Spokesman for the Deutsche Post claimed this was an 'accident'.The usuall screening process for illegal and offensive content didn't work in the case of Nazi post stamp as it is the case in other accidents where content remains blocked; this was explained as result of "unknown causes"
Edited sentence: In 2008 the company accidentally isued 20 Rudolph Hess stamps after Neo-Nazis misused Deutsche Posts Plusbrief Individuell, a "design-your-own" stamp service which delivers pre-franked, personalised envelopes