The U.S. Postal Service wants small businesses to send more direct mail, a.k.a. junk mail, to help the beleaguered agency expand its revenue stream by hundreds of millions of dollars.

In a campaign called "Every Door Direct Mail," the Postal Service is touting a year-old online tool to help small businesses micro-target direct mail. The Web tool allows firms to tap customers by neighborhood or zip code without names or addresses.

The cost to small businesses is 14.5 cents per mail piece. The Postal Service spent virtually nothing to create the online service, tapping existing staff and resources to pull it together, said Paul Vogel, president and chief marketing officer for the Postal Service, at a presentation Tuesday