On Kauaʻi, it's illegal to have new vacation rentals in most communities, and Kollar also wants homeowners to be aware of the consequences.

"You're looking at very steep civil fines, up to $10,000 a day in civil fines. You're also committing a misdemeanor for each day that you engage in the conduct, so you're looking at significant jail time," Kollar said.

VRBO responded with an apology for what it called “a mistake.” Christina Song, with public relations for HomeAway and VRBO said, “within hours of being notified, we proactively reached out to government officials in Kauaʻi to explain the origins of the mistake. We are working to institute procedures to ensure this doesn’t happen again and remain committed to maintaining open lines of communication with local officials, customers and community members.”

Similar letters were also sent to homeowners on Oʻahu and Maui. One was received by Hawaiʻi State Representative Cynthia Thielen whose Kailua home is also neighbor to a number vacation rentals operating without permits.

Kauaʻi, like the rest of the state, is dealing with a housing crisis.

A report released earlier this year by the Hawaiʻi Appleseed Center for Law & Economic Justice found that one in eight homes on Kauaʻi is a vacation rental.

The county has been trying to crack down on the illegal ones.