Scammers are targeting unsuspecting email users by claiming they have missed jury duty and must pay a fine up to €500.
The Courts Service revealed the threat tells people they have broken the law and could be facing arrest for failing to turn up at the Criminal Courts of Justice in Dublin in recent weeks.
A spokesman said staff would never communicate with potential jurors in this way.
"An e-mail purporting to be from the Courts Service is spam and could lead to fraud," the Courts Service said.
"It was not sent from us, by us, or from our IT system. It is a false instrument - designed to gather details about the recipient."
The scam seeks to get an unsuspecting reader to reply to the email address email@example.com if they want to dispute the missed jury duty and threatened fine.
The Courts Service said the address is not one that has been set up or ever used by it.
It is understood a reply to that address prompts a second email which requests bank details and payment of the fine.
The scam, known as phishing, has been reported to the Garda.
The unsolicited email states: "JUROR ID:#456-0023.
"Our records indicate that on the 20/05/2016 at the COURTHOUSE, Ground Floor Jury Office, Dublin Criminal Courts Office, Parkgate Street, Dublin 8 you failed to appear as scheduled for juror service. This is a violation of the law.
"You must contact this office immediately to explain your absence and to reschedule yourself for another juror appearance date.
"Failure to respond to a jury summons is a serious offence and could result in a criminal warrant being issued for your arrest by the court."
The Courts Service urged people to ignore the email.