In the USA, most commercial mass advertising mail is in large printed flyer form, not enclosed in any kind of external envelope. Kinda like this: http://thumb

In the USA, most commercial mass advertising mail is in large printed flyer form, not enclosed in any kind of external envelope. Kinda like this: http://thumbs.dreamstime.com/z/sale-advertising-papers-15592418.jpg http://thumbs.dreamstime.com/z/sale-advertising-papers-15592... The advertisers pay bulk rates to USPS to stuff all this crap directly in our mailboxes. There are some exceptions which arrive in envelopes, mostly to trick you into thinking it isn't just spam mail like the rest of the crap.