Federal workers were caught off guard Thursday by a mysterious email with the subject line “Email Test.”

“This is a test of a new distribution and response list,” the email read.

It included a link to a webpage titled “Federal Government-Wide Email Communication Test.”

“OPM is testing a new capability allowing it to send important communications to ALL civilian federal employees in a single email address. Testing of this messaging system functionality is expected as soon as this week,” the website states.

The message, sent to workers across different agencies in a week of transition, surprised recipients, including some who mistook it for spam, leading some agencies to follow up to clarify with staffers.

Sources told ABC News that the White House has discussed testing a message system where President Donald Trump could message the federal government’s more than 2 million civilian employees.

In a statement posted on X, OPM said: “Federal workers should have received an email testing OPM’s new communications capabilities.”

It’s unclear whether the email test employees received Thursday was associated with the idea of Trump messaging all federal workers.

An OPM spokesperson told ABC News this is the first time the government has been able to send emails to every employee.