Earlier quoted context omitted.
Commercial mass mail for informing isn't sent in envelopes. I presume that's what the parent was talking about.
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.
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.