A chain of emails, acquired by The Retail, Wholesale and Department Store Union (RWDSU) through Freedom of Information Act requests, show Amazon asking USPS officials to conduct an expedited installation of the box by February 7, the day before voting began. While the USPS initially expressed reluctance to the request, they ultimately acquiesced and installed a cluster box unit (CBU), not a normal blue mailbox, on the premises to collect ballots. The box was removed shortly after voting ended. 

Union officials claim that Amazon management then pressured employees to bring their ballots to work and vote onsite, potentially giving the impression that the vote was being held by Amazon and confusing employees about the secrecy of their votes. 

“Even though the NLRB definitively denied Amazon’s request for a drop box on the warehouse property, Amazon felt it was above the law and worked with the postal service anyway to install one. They did this because it provided a clear ability to intimidate workers. We demand an investigation over Amazon’s behavior in corrupting the election,” said Stuart Appelbaum, RWDSU president. 

In the emails, Linda Mercer, a strategic account manager for USPS, wrote to Michael Mann, manager of delivery and customer service programs, that “[redacted], at Amazon HQ would like to kept in the loop…” showing the extent of Amazon’s involvement in the project. 

After the box was installed, Amazon sent a text message to workers urging them to vote against the union and to use the mailbox outside of their facilities—where Amazon surveillance cameras were trained.

“Voting has begun! The US Postal Service has installed a secure mailbox just outside the BHM1 main entrance, making mailing your ballot easy, safe, and convenient,” it read. “Vote now! BE DONE BY 3/1!” Workers had until March 29 to vote. 

The NLRB had already explicitly denied a request by Amazon to host in-person voting on their premises. 

“The timing and urgency of Amazon’s request to USPS, and the nature of the communications with employees about using that mailbox, mean that there is a potential violation of labor law,” Kate Griffith, chair of the department of labor relations, law, and history at Cornell University’s School of Industrial and Labor Relations, told Fortune.  

“The facts that have come out so far certainly raise suspicion of a labor law violation,” she said.  

Amazon told Fortune in a statement that only USPS had access to the box and that it was intended to make the vote easier for employees.

“We said from the beginning that we wanted all employees to vote and proposed many different options to try and make it easy. The RWDSU fought those at every turn and pushed for a mail-only election, which the NLRB’s own data showed would reduce turnout,” said Amazon spokesperson Maria Boschetti. “This mailbox—which only the USPS had access to—was a simple, secure, and completely optional way to make it easy for employees to vote, no more and no less.”

David Partenheimer, a spokesperson for the Postal Service, told Fortune that “the box that was installed – a Centralized Box Unit (CBU) with a collection compartment – was suggested by the Postal Service as a solution to provide an efficient and secure delivery and collection point,” and that he had no further comment. 

Vote tallying is currently underway and will continue Friday. At the end of Thursday, over two thirds of counted votes were against the union: No votes outnumbered yes votes by 1,100 to 463. A total of 3,215 ballots had been cast by Amazon workers.

This would be Amazon’s first unionized warehouse in the United States.