@Viktoria Michaelis - You'll need an akismet privacy policy + opt-in checkbox where it says that your personalized data will be transferred to the USA. http://blog.wpde.org/2011/04/20/akismet-und-datenschutz-einwilligung-per-opt-in-notwendig.html

in the german WordPress version you get a warning after activating akismet that it might be illegal in your country