Opt out of "postal customer" mail

The US Postal Service is raising revenue by selling advertising services. Businesses pay to have advertising flyers delivered to EVERY address in a zip code. I want to opt out! I called my local post office, and I also found this website: citizensformailchoice.com
They appear to be affiliated with catalogchoice.org

If you object to being spammed with physical mail, please speak to your local post office and sign this website's petition. I know web petitions don't do much, so let me know if you discover any other actions to take!

For me, this is not just an annoyance, but a chemical sensitivity issue. The ads are usually newly printed and reek of chemicals.