It isn't? At least in Germany, commerical mass mail is always sent out in envelopes.
I guess that, in this particular case, the reason for the envelopes is to conceal the ads inside them until the recipient has taken the time to open the envelope.
Yep, same here. We do have an option to place a special sticker on the mailbox, which indicates to the postal worker that he doesn't put that kind of bulk commercial material inside.
Well this ain't the norm here (a little bit south from you, still EU). Perhaps it has to do with Germany being always more vary of privacy for history reasons, but is merely a EU recommendation, not enforced by law.
Not targeted for your reply, just clarifying the previous post: I don't appreciate the down votes though, I wasn't stating that OP opinion is right, it was just my understanding of what he meant and trying to understand it.
I guess that, in this particular case, the reason for the envelopes is to conceal the ads inside them until the recipient has taken the time to open the envelope.