Spammers are using YouTube's servers to send massive quantities of unsolicited email, according to security firm Marshal.
The company has warned email users to be wary of messages carrying YouTube invites which appear to derive from the video-sharing site's 'Invite Your Friends' feature, claiming the compromised servers are sending out spam messages from the email@example.com address.
"YouTube users have a facility where they can invite their friends to view videos that they are looking at or have posted. This effectively allows them to email to any address from their YouTube account. This is the functionality that the spammers are exploiting," said Bradley Anstis, Marshal's director of product management.
Marshal said the emails have the same appearance as a legitimate YouTube invite, except they include typical spam content and links to spam websites.
"Spammers are doing this to defeat spam filters and to lower the recipient's guard by making it look as though the messages are coming from a perfectly innocuous email address. YouTube's own Help Center suggests that you exclude the firstname.lastname@example.org email address from spam filtering. The spammers are keenly aware of this."