To check a suspicious ad, intermediary or potentially fake e-mail, you can phone:

mobile.de
Phone 0900 - 1 46 2886 (0900 - 1 go auto)

(€0.99/min for calls from the German Telekom landline, rates for mobile networks may differ) You can reach mobile.de during business hours Mondays through Fridays between 8.00 and 18.00 hours

AutoScout24:
Tel: 0900 - 11 22 412

(€0.59/min for calls from the German Telekom landline rates for mobile networks may differ) You can reach AutoScout24 during business hours Monday through Friday between 8.00 and 18.00 hours

or use the "contact us" form on their website

Other Internet car marketplaces:
please see relevant websites

To report a suspicious advertisement or irregular seller contacts online, please click on the link provided in the ad by the relevant German Internet car marketplace where you found the ad and follow the instructions. Do no buy or sell before matters are clarified!