SPAM mail and email spoofing is affecting more businesses than ever, often making email accounts unusable.

“There has been a sharp increase in the number of businesses seeking help after discovering that their inboxes are flooded with ‘Undeliverable Mail Returned to Sender’ emails,” says Alex Foster, Lead Technical Consultant of BrightVisions.

How it works

This happens when spammers send out bulk mail that appear to be sent from a third party’s email address, to randomly generated email addresses. They conceal the true origin of the emails, instead using email addresses they have found on the internet or by infecting computers and networks with worms such as ILOVEYOU, Klez and Sober.

When the randomly generated email addresses (that the emails are sent to) do not exist, the destination server often sends a reply to the apparent sender, notifying them that the email was undeliverable. The spammers are capable of sending out thousands of spoof messages per second, which means that a large number of ‘Undeliverable Mail Returned to Sender’ emails can flood the apparent sender’s inbox, often making the victim’s inbox unusable and in effect disabling that mailbox.

How to fix the problem

“When a client’s email address has been targeted by spoofers we use an email rule in Outlook to clear the victim’s inbox of the unwanted messages” says Alex Foster,“We then report the incident, with relevant details, to the victim’s ISP. They typically take actions to blacklist the spoofer’s IP address and so greatly reduce the number of these messages that are received.”

How to avoid becoming a victim of email spoofing

Of course, prevention is better than cure and you can prevent becoming a victim of email spoofing by being careful of where you advertise your email address, or using a “public email address” on the internet, and a “private email address” for normal purposes.

The best way to avoid becoming a victim, however, is by keeping your network and computer secure and virus free. Because spoofers often use worms (a type of computer virus) to acquire email addresses and to send spoof messages, it is essential that you protect your network and computers with a firewall and anti-virus software.