The president of the United States’ largest union of federal employees slammed the acting director of a key agency on Sunday for allowing unelected billionaire Elon Musk to make demands of the government’s workforce—and threaten them with termination if they don’t comply.

After Musk posted to his social media platform on Saturday that “all federal employees will shortly receive an email requesting to understand what they got done last week” and that “failure to respond will be taken as a resignation,” a message with the subject line “What did you do last week?” landed in the inboxes of workers across the government.

“Please reply to this email with approx. 5 bullets of what you accomplished last week and cc your manager,” the message states. “Please do not send any classified information, links, or attachments. Deadline is this Monday at 11:59 pm EST.”

The email was sent by the Office of Personnel Management (OPM)—an agency overtaken by Musk lackeys—and it reportedly reached federal judges as well as workers at executive branch agencies.

Everett Kelley, national president of the American Federation of Government Employees (AFGE), noted in a letter to Acting OPM Director Charles Ezell that the email “fails to identify any legal authority permitting OPM to demand the requested information.”

“Federal employees report to their respective agencies through their established chains of command; they do not report to OPM,” Kelley wrote. “Federal employees have a duty to ensure that sensitive information, data, and records are only used and disclosed for authorized purposes. The email was nothing more than an irresponsible and sophomoric attempt to create confusion and bully the hard-working federal employees that serve our country.”

“By allowing the unelected and unhinged Elon Musk to dictate OPM’s actions, you have demonstrated a lack of regard for the integrity of federal employees and their critical work,” Kelley added. “We believe that employees have no obligation to respond to this plainly unlawful email absent other lawful direction.”

Reutersreported that workers at a number of agencies, including the Pentagon and the National Institutes of Health, were instructed not to respond to the email “pending further guidance.”

In a Reddit forum that federal workers have used to vent anonymously about Musk’s ongoing assault on government agencies, numerous users indicated that they have no intention of responding to the OPM email regardless of the potential consequences—another signal of growing outrage and resistance among civil servants.

“I recommend either not responding or if you are ordered to by your manager then proceed with malicious compliance. Fill space without revealing anything useful for their purge,” one user wrote. “Prepare for collective action. If they try to fire en masse, Congress, unions, and legal teams need evidence and voices to fight back.”

“We know by now that this isn’t about efficiency,” the user added. “This is a hostile takeover.”