I thought it was the other way around. Can you cite a source?
Title: Why Do We Subsidize Junk Mail? URL: http://shuthimup.mitzenmacher.net/?p=252 Quote: "So why do we pay 45 cents to mail a first-class letter while direct-mail advertisers pay only 18.5 cents? Can you say “crony capitalism?” Can you say “union busting?” This amounts to nothing more than a very costly subsidy given to the direct-mail industry, at the expense of first-class mailers,"
Title: Snail Mail Spam Subsidies Stuttering Towards A Stop URL: http://blogs.the-american-interest.com/wrm/2011/09/08/snail-... Quote: "the USPS loses billions of dollars each year so that advertisers can send out billions of pieces of spam at below market costs."