I think it depends on why you want to avoid junk mail.

There's a lot of human effort and natural resources consumed in growing timber, cutting it down, shipping it, pulping it, printing it, mailing it, delivering it, recycling it, and pulping it again but into lower-quality product.

Whereas my only wasted labor is to skim through the mail as I walk from the mailbox to the house and then drop the junk into the bin by the door. In the grand scheme of things that part doesn't bother me except insofar as it reminds me of the useless waste of the rest of the lifecycle.