I don't refuse junk mail. I indicate my preference to not have it printed on paper, sent some distance, and hand delivered. I refuse it at the origin, not the destination.
Worst case, the postal service recycles it at origin instead of having to ship it.

Junk mail is junk.
It isn't a resource.
I don't think I've ever received something that meaningfully contributes towards a purchase that I actually want to make.
I buy what I need. I find what I want, I think about if I actually need it, I find local manufacturers, I find local suppliers.
I see if the price difference between local & inter/national is worth the saving (most of the time, it isn't and I'd rather buy from a local manufacturer or supplier, even at twice the price).
Then I decide if I should buy something.

Some paper shipped across the country and shoved through my letterbox is not going to influence my decision AT ALL.
In fact, it's more likely to negatively impact my purchasing decision.
Because here is a company that has excess profits to physical cold-advertise something to me, regardless if I have an interest in it or not.
What a waste of money, resources and time.