Gmail is usually pretty good about filtering unwanted spam messages, but a number of users reported earlier today that their inboxes were suddenly flooded with ads that were apparently sent from their own accounts, according to Mashable.

Users posted to Gmail’s Help Forum, reporting that the messages appeared to have been sent from their own accounts, despite the fact that they were secured with two-factor authentication and updated passwords. The spammers used forged email headers to make them appear as though they came from users via a Canadian telecommunications company called Telus, in order to get the messages past spam filters. Because the messages appeared to be coming from the same user, Gmail filed the message into affected users’ sent folder.

A Google spokesperson told Mashable that it was a “spam campaign impacting a small subset of Gmail users” and that the company had already “actively taken measures to protect against it.” Telus also told Mashable that the messages aren’t coming from its servers and that it’s working with vendors to solve the problem.

h/t Christopher!