Wisconsin Counties are required by law to send voter address verification cards to new voters. Evidently, this law is not enforced, according to this AP article.

Kevin Kennedy, executive director of the state Elections Board, said local officials have said prosecutors rarely follow up on the undeliverable cards, even though they could lead to charges if voter fraud was involved.
“Municipalities have complained for years the D.A.’s don’t do anything with it,” Kennedy said. “That’s the feedback we get when we hold training sessions.”
In Milwaukee, there have been “several hundred” cards returned as undeliverable, said Lisa Artison, executive director of the Milwaukee Election Commission. The cards are still arriving and have not yet been sent to the district attorney’s office, she said.
In Dane County, District Attorney Brian Blanchard said he didn’t know how many cards had been returned but noted a clerk had bundled up a 6-inch stack.