We got dozens of such faxes each month at our business for the entire eight years. Not only health insurance "offers" but investment "opportunities", vacation offers, etc... We signed up for the do not call list too, to no avail.

Some of them would change the company name and refax after we requested them to take us off their list. We used an inkjet fax machine there too so it was expensive. We had to leave it on all night though. Some vendors faxed at night and the occasional customer.