The Sender Policy Framework (SPF) authentication method tries to determine whether the email is legitimate and should be delivered to the inbox. A recent deliverability study shows an increasing reliance on this framework. This means that marketers should make sure their SPF records are up to date, if they want to maintain their inbox delivery rates for their permission-based messages.

    The study is titled Lyris’ EmailAdvisor ISP Deliverability Report Card for Q2 2007, and is a quarterly research study that monitors deliverability rates for permission-based email marketing messages. The study measured the full delivery trajectories of more than 436,000 permission-based email marketing messages using ISP domains in the United States, Canada, Europe and Australia.

    Stefan Pollard, Director of Consulting Services at EmailLabs, stated: “This is the first time we’ve seen SPF checks start to creep into content filter tests, which means that receivers are starting to verify that a sender’s SPF authentication record is accurate. This is new. And the good news is that it’s an easy fix for marketers – in fact, it’s completely in the sender’s power to make sure the records are accurate at all times. Don’t assume it’s the responsibility of your system administrator. If you’re responsible for the email program, you need to realize the importance and test it yourself.”

    The study shows that permission-based email messages make it to U.S. ISP inboxes roughly 75 percent of the time. AIM.com led the pack with 97 percent inbox delivery, a full 10 percentage points higher than second place RoadRunner SoCal – both of which didn’t even make the top ten last quarter. Rounding out the top performers – all getting inbox delivery rates higher than 80 percent – are Verizon, USA, Compuserve, IWon, AOL, Juno, Mac and Netzero.

    Failing an SPF check carries a heavy penalty – 2.6 points from the current Spamassassin test, on a Bayesian scale that identifies a message as spam when it reaches 3.0 points or higher. That’s more than double the penalty for any of the other top ten spam triggers identified. Marketers sending permission-based emails to U.S.-based ISPs still land in the junk/bulk folder almost 16 percent of the time. XO Concentric far exceeds any other ISP – banishing 56 percent of invited email to the junk/bulk folder. Next in line are SBC Global and Bell South, both junking 30 percent of permission-based email, and Yahoo at 26 percent. MSN Network, GMail and Hotmail all come in at 18 percent. Rounding out the top ten are PeoplePC, USA and Earthlink. At the other end of the spectrum – AOL only delivered 1.94 percent to the junk/bulk folder.

The complete study in PDF format is available at http://www.lyris.com/resources/reports/deliverability_report_Q22007.pdf.