The junk mailers would still mail their advertisements. The USPS picks them up and scans them at their pickup point, or at the nearest processing facility (they

The junk mailers would still mail their advertisements. The USPS picks them up and scans them at their pickup point, or at the nearest processing facility (they already do this, to automatically shunt mail to the proper zones). Mail that I designate as "trash" via the iPhone / web app gets recycled before it actually gets shipped across the country, or, if it's already shipped, then when it next gets processed at my local processing facility. So the advertisers still pay the full rate; I just have the option of intercepting it before it makes it to my mailbox. If I don't act in time, it gets delivered, just like normal.