What Is An SPF Record? What Do I Need To Do About It?
a significant majority of spam comes from forged addresses, a Sender Policy Framework (SPF) standard is being implemented by a number of ISPs and mail hosts, including several major providers (Hotmail, Yahoo, AOL, etc). Those providers require SPF to be used in order to allow mail through their networks. Mail systems need SPF records for their domains if they want their mail to be accepted by those providers.
You will need to create/modify your domain's SPF record to provide the IP address of the mail server(s) or network that you use to send mail.
To generate an SPF record, we recommend using the SPF Wizard at http://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/. You will need to enter your domain name into the Let's set up SPF records for field, then click Begin. Based on your answers, an appropriate SPF record will be displayed at the bottom of the page. If you want an explanation of the record at any time, you can click Explain.