Those white, typed, one-page political flyers that Vero Beach homeowners throughout the city found taped to their mailboxes early last week?

The ones urging the “Citizens of Vero Beach” to vote “YES” on the last referendum on the ballot – the one that would require voter approval for all but the smallest improvements to city parks and other charter-protected properties?

They were put there in violation of federal law, which prohibits flyers from being affixed to mailboxes.

According to the United States Postal Service website: “No part of a mail receptable may be used to deliver any matter not bearing postage, including items or matter place upon, supported by, attached to, hung from, or inserted into a mail receptacle.

“Any mailable matter not bearing postage and found as described above is subject to the same postage as would be paid if it were carried by mail.”

There were no postage-paid stamps on the flyers, which were especially visible in the Central Beach area.

Depending on how many mailboxes were violated, the cost of reimbursing the USPS for the unpaid postage could be substantial – if the agency wants to pursue the matter.

So could this: The penalties for such violations include fines up to $5,000 per occurrence for individuals and up to $10,000 per occurrence for organizations.

Perhaps that’s why whomever was responsible for distributing the flyers did so anonymously. The letter was unsigned and contained no mention of any candidate, political affiliation or citizens group.

The flyer, however, staunchly endorsed the referendum authored by the Vero Beach Preservation Alliance, which began as a neighborhood effort to oppose the expansion of the municipal marina but has mysteriously morphed into an anti-development movement that threatens the wildly popular Three Corners project on the mainland’s waterfront.

If the VBPA was connected to the flyer, it wasn’t saying. An email sent Sunday to the alliance’s attorney, Lynne Larkin, who was asked if the group was responsible for the flyers, produced no response.

The way the letter was written, though, hinted that the flyers might’ve been a one-person operation – or at least an endeavor on behalf of one person, perhaps one of the candidates in the current City Council race.

Oddly, the letter’s first paragraph began with the word, “I,” and not “We,” as you’d expect from a political party or citizens group.

Also curious were the contents of the second and third paragraphs, which pertained more to the City Council election than to the alliance’s referendum:

“The current city council, which includes two that are running for re-election (Honey Minuse and Bob McCabe) have already given $1,000,000 of our city’s money to a group that is building an athletic field on non-city-owned property. Yet at the same time they are charging city families to use facilities owned by the city.

“Are councils like this, the people we want in charge of your money and how Vero Beach looks in the future?”

The next paragraph then attempts to scare city residents, warning that the current City Council will turn Vero Beach into “St. Lucie” – minus the Port, apparently.

The letter closes with two words: “Thank you,” and there’s a copy of the alliance’s referendum on the other side of the page.

That, too, could be a problem.

County Supervisor of Elections Leslie Swan said she hadn’t seen the flyer, but if its purpose is to promote a candidate, referendum or other political issue, Florida law requires that it include a disclaimer identifying who is responsible for distributing the advertisement and who paid for it.

The flyer contains no disclaimer.

“Any complaint would need to go to the Florida Elections Commission,” Swan said, adding that if the flyers were funded by a candidate, the expenditure must be included in his or her campaign finance report.

Farroh Ferguson, the USPS’ Vero Beach-based customer service supervisor, confirmed the local Post Office had received a complaint about the flyers and already had taken action.

In an email last weekend, Ferguson wrote that the Vero Beach postmaster is aware of the incident and USPS management has “spoken to the alleged company involved in this matter” and was “assured that this activity will cease.”

As of Monday afternoon, Ferguson had not responded to a follow-up email seeking the name of the “alleged company” responsible for the flyers and an explanation as to how the USPS identified the offending party.