One of the biggest problems with e-mail is the complete lack of an inherent security model. Like the telephone, most people have come to take e-mail for granted; expecting that it simply works. Most e-mail users do not know how easy it is to forge almost every aspect of an e-mail message. We have all received spam that, when viewed in our e-mail client (Outlook, Entourage, Gmail, etc.) appears to have been sent to us, from us. How can this happen?
There is a common misconception amongst many in the e-mail security space that anti-fraud technologies like Sender Policy Framework (SPF), SenderID and Domain Keys Identified Mail (DKIM) are part and parcel anti-spam technologies. While it is true that anti-fraud/anti-forgery technologies have a nice side-effect of preventing some spam, this is not their main goal. In addition, by lumping these imporant technologies in as simply anti-spam misses the point and tends to dimish the importance of these technologies.
Protecting your domain from e-mail forgery is up to you; the owner of the domain. Does your domain publish a Sender Policy Framwork (SPF) record (http://www.openspf.org/)? If not, why? What are you waiting for? Is your inbound e-mail checked to see if the sender’s domain publishes a SPF record? If not, why? After all, if the sender’s domain administrator has elected to take domain forgery seriously, you should as well. Finally, are you recognizing DKIM (http://www.dkim.org/) signatures for inbound e-mail and is your e-mail server signing outbound e-mail?
In case you are wondering… Google, eBay, Yahoo, Cisco, and many other large companies are now on the DKIM bandwagon.