Hi Dan
Operating anti-spam blacklists, adding my email address to all kind of newsletters, online contests etc. apparently is a common revenge from spamers who get listed. Unfortunately too many ESP operators still don't understand that 'real' double opt-in would solve the issue.
According to the Swiss 'Datenschutzgesetz' you can ask the sender of a newsletter or unwanted email advertizement to send you all the information related to your email address from his database including the IP address and time from which the subscription happened. This works quite well with companies within switzerland and the EU.
As, at least in switzerland, an operator of a newsletter, has to provide proof of opt-in, this is the proof he has to provide.
With that information, you can send a complaint to the ISP operating the said IP address and hope that he will issue a warning to his customer, or you could try to get legal actions against that ISP's customer for identity theft or Urkundenfälschung as you said.
-Benoît Panizzon-