Billions of Gmail users across the world are being targeted for their personal details.

Users of the popular email service from Google are being warned to keep an eye out for a new scam circulating online.

Fraudulent scammers are attempting to collate personal details from users by sending a seemingly harmless message.

US security company Barracuda Network warned: "Bait attacks are one technique attackers are using to test out email addresses and see who’s willing to respond."

The company adds scammers are "working to collect information that will help them improve the odds that their attacks will succeed".

What the Gmail scam will look like

Victims are initially sent a blank message which reads “hi” in the subject line.

This approach means the email address connected to the scammers will bypass any spam filters.

It’s because the email will not include phishing links, malicious attachments or malware that is usually picked up by spam blockers.

A second email will then be sent by the scammers impersonating a person or firm they know from their details.

Yahoo and Hotmail users affected

Experts have warmed users of Yahoo and Hotmail scammers are also being inundated with fraudulent messages.

Experts say adding extra security measures including specific software to identify scams will help protect users from fraudsters.

Users are also reminded to mark anything they suspect is a scam in their spam folder which will help protect them in the future.

Billions of Gmail users across the world are being targeted for their personal details.

Users of the popular email service from Google are being warned to keep an eye out for a new scam circulating online.

Fraudulent scammers are attempting to collate personal details from users by sending a seemingly harmless message.

US security company Barracuda Network warned: "Bait attacks are one technique attackers are using to test out email addresses and see who’s willing to respond."

The company adds scammers are  "working to collect information that will help them improve the odds that their attacks will succeed".