David Poellhuber, ZEROSPAM: An improper use of SPF can make you block your own email
June 2009 by Marc Jacob
SPF, or Sender Policy Framework, is a system that, when used properly, enables you to specify the authorized outgoing email gateways for a domain and thus protect it against spoofing.
A growing number of organizations publish SPF records, a simple and free procedure that is well documented on www.openspf.org.
In this context, SPF is earning its stripes and millions of domains now publish SPF records – although they are not always valid. An SPF record that is not valid or up to date can do more harm than good. ZEROSPAM has indeed recently noticed that many domains had their email blocked because of invalid or multiple records. As more and more organizations publish SPF records, a growing number of email services is starting to validate them and could potentially block your messages if you have an invalid SPF record.
Therefore, it is in the best interest of domain names owners to make sure their SPF record has a valid syntax, is unique, and up to date. A free SPF validation tool is available on www.kitterman.com/spf/validate.html.