Federal employees are suing Elon Musk after the entire workforce received an email instructing them to explain their work or face being fired.

The suit, filed by unions and advocacy groups, alleges that the email violates laws regarding federal workforce and that the Office of Personnel Management (OPM), which sent the email, does not have the authority to make the demand.

Employees found the email in their inbox on Friday. It asked them to provide a list of five accomplishments for the past week, without revealing classified information.

The message sparked confusion and alarm among workers, particularly after several agency leaders – including Trump appointees – told staff not to respond.

But Musk maintained on X that he was acting on instructions from President Donald Trump and that a failure to reply to the email by Monday night “will be taken as a resignation”.

This meant that, like many of Musk’s directives, federal workers faced uncertainty over their employment. Many also expressed confusion at the competing guidance they had been given by their respective agencies.

Over the weekend, thousands of public health workers at the Department of Health and Human Services (HHS) received a series of conflicting directives regarding the email.

They first received guidance that the instruction was legitimate, and they were told to read and respond to it by Monday, according to an email seen by the BBC.

HHS employees then received an update, directing them to “pause” activities related to the email. HHS officials were working with the administration’s personnel office to comply while being “mindful” of the agency’s sensitive activities, the new guidance said.

“They’re succeeding in driving us insane,” said one employee who works under HHS, and asked not to be named for fear of retaliation.

Staff was still waiting for agency leadership to meet and decide next steps as of Monday, the employee said.

Some federal employees said they had contemplated small acts of rebellion, like responding to the email with recent tasks such as answering hate mail and firing their colleagues.

The US Department of Justice, Department of Defense, and Federal Bureau of Investigation have all recommended their staff not respond to the email, which had a Monday night deadline. All are currently run by Trump appointees and loyalists.

In a statement posted to X, Department of Defense official Darin Selnick told staff to “please pause any response” to the email.

“The Department of Defense is responsible for reviewing the performance of its personnel and it will conduct any review in accordance with its own procedures,” the statement said.

Kash Patel, Donald Trump’s new head of the FBI who has railed against federal employees, also issued a similar direction to the agency’s staff, but the Department of Transportation directed its employees to follow the email’s instructions.

The new lawsuit responding to the email is attached to one filed last week in California, which seeks to block the Trump administration’s mass firing of federal workers.

The revised version alleges that “no OPM rule, regulation, policy, or program has ever, in United States history, purported to require all federal workers to submit reports to OPM”.

Major federal employee unions, including the American Federation of Government Employees, as well as advocacy groups like Vote Vets are part of the lawsuit. A group called the State Democracy Defenders Fund and the California-based Altshuler Berzon law firm represent them.

Musk’s latest tactic to cull federal employees has raised concerns it could reveal classified information or violate government procedures.

“Federal employees have a duty to ensure that sensitive information, data, and records are only used and disclosed for authorized purposes,” American Federation of Government Employees president Everett Kelley wrote to OPM leadership.

Musk and his Department of Government Efficiency have taken aggressive action to cut down the federal workforce. They have bombarded government employees with emails sent via through OPM, threatening layoffs, offering buyouts with questionable terms, dismissing probationary employees, and ordering managers to make lists of employees to cut.

The efforts have sparked anger from within the federal workforce and a barrage of lawsuits, but this latest order has publicly countered from within agency leadership itself.

Max Stier, president of the nonprofit Partnership for Public Service, called the email “yet another example of the new administration’s contempt for public servants and public service that will lead to further confusion, anxiety and waste”.

Trump’s allies have praised the idea of forcing government employees to justify their work.

“I think it’s a great idea, you do it in private business all the time,” Rep Tim Burchett, a Republican from Tennessee, told News Nation. “You have to have accountability.”