Advertising for these events is important so folks can know about them. Except when a notice about the event is taped to an NBU (Neighborhood Box Unit - that's a mail box). If one checks with the USPS I believe they will find that it is a violation of Federal law to do this. Now, granted, nobody was harmed, mail delivery wasn't interrupted, it's just an "in your face" type of thing.
See the image below, and click on it for a larger version.
