Dropbox has emailed many of its users, urging them to reset their passwords.
The popular cloud storage said the move was related to the theft of an old set of Dropbox credentials, dating back to 2012.
So the users the company has contacted are those who created Dropbox accounts before mid-2012 and have not updated their passwords since that time.
Dropbox disclosed in July 2012 that some users were getting spammed, and the cause appeared to be the theft of usernames and passwords from other websites.