This has happened to me... more than once.

You get a notice that you have a piece of registered mail in the post office waiting for you. You go tot eh post office, wait 45 minutes or so in line, and end up discovering that the item that you wasted a good portion of your morning for is nothing but a wall calendar you never asked for or a catalog or brochure you could not care less about...

MKs Moshe Gafni and Uri Maklev (UTJ) have proposed a law by which companies sending you registered mail would have to list the details of the sender on the notice - his name and address. This way you will know who it is from and can decide for yourself whether or not it is worth your time to go pick it up. A person has the right to know who is sending him mail and decide whether he wants to go get it or not.

One caveat is that the new law will not apply to public bodies obligated by law to send their notices via registered mail. The relevant government bodies are excluded due to the concern that if the recipient would know in advance that a letter is coming from the police or the courts or some other official body, they very well might refuse to go pick it up.

The proposal passed its initial reading by a vote of 45-0.
source: Calcalist

so, soon, when the law is finalized, if your registered mail comes with no details of the sender, you might want to avoid going to get it - it might be a ticket from the police or something similar. Otherwise it should have the details on it so you can choose not to go, depending on what kind of calendar it is...