Return Path Certification: Is there value?

Recently, a client asked me, what is the value to ISPs in utilizing Return Path Certification (formerly known as Sender Score Certified)? Meaning, why do ISPs use it? A number of ISPs both big and small have spam filtering systems that treat certified IP addresses differently than non-certified IP addresses. Sometimes spam filtering is bypassed, effectively guaranteeing inbox delivery. Sometimes rate limits are greatly loosened, allowing mail to flow in much faster. Sometimes it is used as just one of the many variables used by the ISP to determine inbox placement versus bulk folder placement versus rejecting the mail outright.
The question is a little different than usual. It’s not a question of, why should a sender become certified? It’s a question of, why would an ISP choose to use the certification data on the inbound side? It’s a neat question, one that I’ve never really heard answered by an ISP before.
Curious, I asked a number of ISP folks for their opinions on this topic. Assuming few would want to discuss this on the record, I made it clear that I wouldn’t mention any names. What I found was that nobody had anything bad to say about Return Path Certification. One person I talked to said that they don’t really give it that much thought–it just works. Many thousands of inbound messages come in from certified IPs, and they never get any spam complaints about those messages, so it’s all good. That’s hardly a scientific review process, but hey, if it works for them…
Another told me that Return Path Certification “helps us by helping senders improve the overall quality and desirability of email that comes into our network.  This is great for our customers who rely on email communications in their daily life and expect of us predictable delivery of their key emails.”
The overwhelming message I received from ISPs was that they like Return Path Certification because there’s a strong implication that those mail streams are already clean and that the sender’s practices have already been vetted. They feel that Return Path is doing the hard work of insisting on the right best practice requirements and monitoring appropriate metrics to ensure that good guys get certified and bad guys don’t get certified. If a sender can get certified, it is as though they are announcing to the world (and ISPs) that they have already been reviewed and seem to be doing things correctly.
10/14/2010 Update: Return Path just notified certified senders that their mail will now proceed directly to the inbox at Comcast, presumably bypassing some or all of Comcast’s usual spam filtering.
Guest post by Al Iverson.