Gmail is usually pretty good at filtering out unwanted spam messages, but a number of users previously reported that their inboxes were suddenly flooded with ads that seemingly were sent from their own accounts, according to Mashable .
Users posted to the Gmail Help Forum stated that the messages appeared to be sent from their own accounts, even though they were backed up with two-factor authentication and updated passwords. The spammers used fake e-mail headers to make them look like they came from users through a Canadian telecommunications company called Telus to pass the messages through spam filters. Since the messages appear to come from the same user, Gmail put the message in the sent folder of the affected user.
A Google spokesperson said Mashable that it is a "spam campaign that affects a small group of Gmail users" and that the company has "actively taken action to protect it "] Mashable that the news is not coming from their servers and that it is working with the manufacturers to solve the problem.
h / t Christopher!