Gmail users mystified after spam messages start appearing in Sent folder

Some Gmail users have been left confused and concerned after discovering spam emails in the Sent folder of their accounts.

Had they blacked out and actually messaged people about weight loss services and “growth supplements”? Had somebody stolen their Gmail login credentials and broken into their accounts?

Fearing the latter, some users changed their passwords. However, new spam messages kept appearing.

Related: Netflix scam tricks users by exploiting Gmail quirk

According to Google, spammers used what the company describes as “forged email headers” to make it look like Gmail users were receiving emails from themselves, which in turn led to the service thinking they’d also sent those messages.

“My email account has sent out 3 spam emails in the past hour to a list of about 10 addresses that I don’t recongnize,” Gmail user Louis Morton wrote in a post on the Gmail Help Forum over the weekend.

“I changed my password immediately after the first one, but then it happened again 2 more times. The subject of the emails is weight loss and growth supplements for men advertisements. I have reported them as spam. Please help, what else can I do to ensure my account isn’t compromised??”

Other users said the same thing had happened to them and, stranger still, many of those spam messages appeared to be linked to Telus, a Canadian telecoms firm. Telus quickly confirmed that it had nothing to do with the messages.

It’s a slightly dizzying mess, which Google has now fixed.

“We are aware of a spam campaign impacting a small subset of Gmail users and have actively taken measures to protect against it,” a Google spokesperson told Mashable. “This attempt involved forged email headers that made it appear as if users were receiving emails from themselves, which also led to those messages erroneously appearing in the Sent folder.

“We have identified and are reclassifying all offending emails as spam, and have no reason to believe any accounts were compromised.”

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Were you affected by the campaign? What did you suspect had happened? Share your thoughts son Twitter @TrustedReviews.