With a day until the New Hampshire primary, some residents of the state are receiving "voter shaming" mailers from an unknown group that are meant to embarrass them into turning out.

The letters, which warn residents that "your neighbors and other people you know will all know who voted and who did not vote," include a "voter report" purporting to show voting records for the 2012 general election and 2014 primary and general elections.

Residents who received the letters Monday said they were sent in envelopes reading "IMPORTANT TAXPAYER INFORMATION ENCLOSED."

"This appears to be an attempt to intimidate NH voters," wrote William O'Shaughnessy, who said he's an independent voter in Bedford, New Hampshire. "I understand that this is public information, but this use of the information is outrageous."

William O'Shaughnessy A letter sent to New Hampshire resident William O'Shaughnessy warns him that everyone will know whether he votes on primary day.

Other New Hampshire voters, including both registered independents and Republicans, have also reported receiving copies of the letter.

"If I were to find out prior to tomorrow's vote who would stoop this low to garner votes, even if I was going to vote for them, they would lose my support," one recipient wrote to HuffPost. "I have no interest to know who in my area did not vote and am extremely angry that some organization or candidate supports this type of blackmail tactics."

The mailers offer no information on which, if any, campaigns they're linked to. The envelopes give the return address as a P.O. Box in downtown Manchester, New Hampshire, while the bottom of the letters say they're "Paid for by Public Policy Matters," a group with no apparent web presence. No PAC with that name has been registered either in New Hampshire or with the FEC, according to The New York Times.

The language used is nearly identical to the wording of one letter in a 2008 political science study on voter turnout. That study, which sent different mailers to Michigan households, found that the "social pressure" of knowing their neighbors could see their voting record was unusually effective at driving people to the polls.

Since then, campaigns and organizations on both sides of the aisle have picked up on those findings, using similar mailings to nudge voters -- and often generating substantial backlash.

Most recently, Ted Cruz's campaign sent Iowa voters a controversial mailer with the heading "VOTING VIOLATION," warning recipients that "you are receiving this election notice because of low expected voter turnout in your area."

The Huffington Post wants to know about all the campaign ads, mailers, robocalls, candidate appearances and other interesting campaign news happening by you. Email any tips, videos, audio files or photos to openreporting@huffingtonpost.com.