You are incorrect, but only technically. You can opt out of EDDM at the DMA website, but the whole chain of custody for handling the opt-out is so convoluted that it's effectively pointless.
What happens is that the DMA maintains an opt-out list which the mailers are supposed to check. Then they add your address to a cover sheet called a facing slip which they pass to the local USPS when they hand off the ads. The USPS is then supposed to give those addresses to the mail carrier and the mail carrier is supposed to check it when delivering the ads.
In reality, since EDDM is intended for blanket coverage of local ads, practically no local advertisers bother or are even aware of the opt-out list, and even if they did the mail carrier will probably ignore the list, so signing up has little effect.
The best way to "opt out" is to be a dick to your mail carrier. Put a sign on your mailbox that says "NO EDDM: unaddressed mail will be refused" and then follow through on your threat by forcing your carrier to take back all EDDM ads the next day. My mail carrier quickly realized that there was no point delivering EDDM ads to my house.
You just write REFUSED on the unopened letter. It's best to scribble out your address to prevent their automated system from simply re-delivering it to you. I do this on postcards as well (which cannot be opened by definition) and they will take those. If it's first class mail they'll return it to the sender, otherwise they will take it back and discard/recycle it.
Do you know if this might work for a PO Box as well? I once spoke to an agent at the window of the post office where my PO Box lives about this. I asked if I could put some sort of notice like the one you're suggesting, but the person claimed there was no way to stop receiving fliers in my box because the companies pay a lot for them to be delivered (paraphrased).
At my post office they refer to the coupon crap as ADVO. I put a NO ADVO sticker in my box. Anything that doesn't have my address on it goes into the community outgoing mail slot. It gets better for a while then someone goes on vacation or quits and we go through it again.
What happens is that the DMA maintains an opt-out list which the mailers are supposed to check. Then they add your address to a cover sheet called a facing slip which they pass to the local USPS when they hand off the ads. The USPS is then supposed to give those addresses to the mail carrier and the mail carrier is supposed to check it when delivering the ads.
In reality, since EDDM is intended for blanket coverage of local ads, practically no local advertisers bother or are even aware of the opt-out list, and even if they did the mail carrier will probably ignore the list, so signing up has little effect.
The best way to "opt out" is to be a dick to your mail carrier. Put a sign on your mailbox that says "NO EDDM: unaddressed mail will be refused" and then follow through on your threat by forcing your carrier to take back all EDDM ads the next day. My mail carrier quickly realized that there was no point delivering EDDM ads to my house.