If you receive an e-mail purporting to be sent by a U.S. District Court, ordering you to testify before a Grand Jury, delete it: You are not being served.

Rather, this online hoax—reportedly sent to tens of thousands of people last week—is a phishing scam that provides a link with instructions to “download  the entire document.” When the link is clicked, it unleashes a computer virus to capture sensitive data such as passwords.

What you need to do: Delete the e-mail without opening it or clicking on the link.

The phony e-mail claims to originate from subpoena@uscourts.com—and many falsely claim to be served by “O’Mevely & Meyers,” a slight misspelling of the international law firm of O’Melveny & Myers LLP. That firm has issued a warning on its website.

Although riddled with other misspellings, the e-mail bears the U.S. Courts seal and a docket number and is authentic-looking enough that the FBI and U.S. Courts have issued warnings. Already, at least 1,800 e-mail recipients have clicked on the link, estimates VeriSign’s iDefense Labs, a cybersecurity company.

In reality, federal and other courts do not issue subpoenas via e-mail; even if they did, their e-mail addresses end in .gov, not .com.

If you receive one of these e-mails, you can file a complaint with the Internet Crime Complaint Center.