While we have seen a 150% increase in overall spam there are specific spam tactics that are seeing huge increases as well. The latest trend in spam appears to be email messages that spoof non-delivery reports (NDR), the messages users receive when their email bounces back from a non-existent email address or system failure.
NDR messages are usually legitimate, but this mail server function is being exploited by spammers using the sender’s real name. Spam content is sent as an attachment to the fake NDR.
Since most NDRs are legitimate emails and part of the mail server functionality, many traditional email filtering techniques do not detect or block them, he said.
Spam now makes up close to 90 percent of all global email, representing billions of spam messages each day. Most spam is generated automatically through botnets – networks of PCs that have been taken over by attackers.