Ok, so they used a template on the paper, namely "{first}.{last}@hhi.fraunhofer.de", while the email addresses, if the names are applied to the template, do in

Ok, so they used a template on the paper, namely "{first}.{last}@hhi.fraunhofer.de", while the email addresses, if the names are applied to the template, do in fact yield valid email addresses. It sounded as if they were using "john.doe@hhi.fraunhofer.de" while in reality it was an invalid email address ("because there’s no match with the email address"), that he would have tried to claim co-authorship via his "real" address, which might be something like "j.doe2@hhi.fraunhofer.de" (but luckily is not). It's all clear now. Thank you for your explanation.