2 years ago before I left Germany someone I knew said that he will file a lawsuit against me :( I am now not in Germany and I didn't give this guy my address in my current country but how can I know if he really did it? who should I contact?
You're supposed to deregister with the registration office before moving out of country. This process involves giving the registration office your new address abroad.
If you get sued, I assume that the court will first try to look up your address with the registration office. If you've done your homework, they will see where you moved and then try to initiate international process service. International process service is a science unto itself, so I won't go into detail with that. Short version is, the exact procedure for arranging international process service depends on the destination country and if everything goes fine, you should receive written notice that there is a lawsuit against you.
If the court is unable to find your new address at the registration office, they will try to serve you at the last known address they can get hold of.
This means that a postal operator will be instructed to serve you at your last home in Germany. This will of course fail because you're no longer there. (At this point, I assume that you have removed the name plate on your letterbox. If your nameplate is still there, you have a problem because your lawsuit may now be served on a letterbox you no longer live in.) The mailman will then check if there is a mail forwarding order for your address and if the forwarding address is foreign, the paperwork goes back to the court with your new address and a remark that international forwarding of process service is not permitted. THe court will then try to initiate international process service at your new address.
If the postal operator has no fowarding order, the item will go back to the court as undeliverable. In this case, the court will serve you by public notification. This means that a note will be put up at the notice board of the court telling you to pick up the papers at the court.
If you don't do that, process will be deemed served on you 14 days after the note was posted on the notice board.
Make sure that you are properly deregistered with the registration office. This includes informing the registration office about your new address. (This is required by law.)
To be on the safe side, I would also recommend the following steps:
• Make sure that the nameplate on your door, on the intercom panel and on your letterbox have been removed. Anyone showing up at your house should be able to tell that you no longer live there.
• Seal your letterbox with adhesive tape after collecting your mail for the last time. Mailmen have the habit to remember names instead of reading name plates every day. This way, your mail won't end up in a dead letterbox.
• Set up a mail forwarding order with Deutsche POst AG. This should be done 3 weeks before vacating the home.
• If there is a regional mail company in your area, also set up a mail forwarding order with them.
If you're the paranoid guy, there's even more you can do:
• Periodically renew your mail forwarding order(s)
• Contact the court and ask if they have a lawsuit for you
• Inform the plaintiff about your new address. Then they can't claim not to know where you live.
• Inform the local bailiff about your new address or ask them if they were instructed to serve something on you.