Starting in November, Microsoft's Hotmail will extend its checking of SPF records for senders of incoming email. This will raise the bar for email senders in Hotmail's quest to rid its users' inboxes of spam.
Currently, absence of an SPF record does not lead Hotmail to believe that the message is any more or less likely to be spam. From November, Hotmail will see the absence of a record as a sign that a message might be spam.
This move illustrates the steady progress that the industry is making towards a world where email "senders" can't be forged. Stamping out forgery will give us a firmer foundation for monitoring the reputation of senders.
It also highlights the need for domain owners to publish SPF records as soon as possible. On the one hand, 25% of mail using SPF is encouraging, what about the other 75? Do you own a domain? Publish an SPF record already! Ferris Research recently wrote a report showing how to do this.
Expect other email providers such as AOL, Earthlink, and Gmail to follow suit. They will no doubt discuss this at the Email Authentication Summit on July 12th in New York.