Sender Policy Framework or SPF is an email validation system that allows receiving systems to verify the sending organization. What does this mean in simple terms? Less Spam. Seventy percent of all email currently is spam.

 

The SMTP Loophole

The general issue with Email and the STMP protocol is that any computer can send email claiming to be from any source. Spammers exploit this by sending messages from forged email addresses. Phishing attempts rely on this loophole to dupe unsuspecting users into revealing sensitive information. Spam has a real financial consequence when a computer is infected and must be cleaned.

How Does SPF Work?

The owner of a domain uses external DNS TXT records to list the systems that are allowed to send email on its behalf. When you send an email the receiving system will check for an SPF record, if one exists it will examine the allowed systems versus the sender of the current email. If these records do not match the email is rejected. This can dramatically cut down the amount of spam, NDR backscatter, and phishing emails an organization receives.

Below is an example of Google's SPF record. You can see in this example there are many ways to list available systems. You can use an IP range, a DNS "A" record, MX records, and event PTR records.

v=spf1 include:_spf.google.com ip4:216.73.93.70/31 ip4:216.73.93.72/31 ~all

So, Does My Company Have One?

You can use the website www.mxtoolbox.com to check your current SPF records. If you don't have one you are missing a major opportunity to easily deter spam.

Need Help?

There are wizards available to help you create your SPF record.

https://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/

I would be happy to assist you in creating your records. You can contact me at ethompson(AT)ali-inc(DOT)com