At least 50 to 100 Florida residents have received bogus letters over the past few days telling them they're not eligible to vote. The letters, postmarked in Seattle and sent under the names of actual county election supervisors in Florida, claim that "information" about the recipient's citizenship status has come to light, "bringing into doubt your eligibility as a registered voter." A spokesperson for the Florida Secretary of State's office tells NBC News, "We believe these letters appear to meet the standard of voter intimidation." The FBI and US Postal Service are investigating. "We're looking at everything from civil rights violations to election fraud (and) everything in between," says an FBI spokesperson.