E-mail authentication: It's time

Al Iverson, ExactTarget

ISPs like Hotmail have been pushing e-mail authentication for years. I've been talking about Sender ID and Hotmail for more than two years now and Meng Wong (now of Karmasphere) has been educating senders and receivers on why sender policy framework (SPF) is important since at least mid-2004.

For a long time, it seemed like a solution in search of a problem. Common questions included, what does e-mail authentication do, why should one invest in a new technology, and if mail is getting through fine. There simply didn't seem to be a good enough, or compelling enough reason for most senders to start authenticating their mail.

But now the industry recognizes that there are significant delivery benefits for senders who authenticate their mail.

There are now three primary authentication technologies in play: Sender ID, SPF and DomainKeys/DKIM (DomainKeys Identified Mail). Here's a simple overview.

Sender ID just got very important at Hotmail. Sender ID is an integral component of getting your e-mail to any inbox at Hotmail. If you're not doing Sender ID, or your Sender ID records are set up incorrectly, you're going to have issues soon, if not already. Hotmail has clarified on numerous occasions and in numerous venues that if you publish a Sender ID record, and do it correctly, it improves your ability to deliver mail.

DomainKeys (soon to be replaced by DKIM) is the authentication technology most important to Yahoo. What's the benefit? If you want to participate in Yahoo's feedback loop, you need to sign your mail with DomainKeys. If you don't have DomainKeys authentication in place, you won't receive spam complaint data back from Yahoo users. Senders who utilize feedback loops enjoy better deliverability. Yahoo is a large enough receiving site that any spam-blocking issues are sure to have a huge negative impact on e-mail performance.

SPF matters, too. Sender ID is backwards-compatible with SPF, so you need to be doing at least one or the other to prevent Hotmail issues. SPF will also give you a modest delivery boost at a few other ISPs, with the promise that more are to come. Since it's the easiest technology to implement, at the very least, you should be utilizing SPF. It's a simple text record you put in DNS, and it's something you should immediately task your server administrators (or e-mail service providers) with helping you implement.

Authenticate today and the benefits won't be limited to better deliverability with Hotmail and participation in Yahoo's feedback loop. As more and more receiving sites and spam filters begin looking for e-mail authentication, the benefits will multiply.

Al Iverson is director of privacy and deliverability at ExactTarget. You can reach him at aiverson@exacttarget.com.

 (This article first appeared in the 2007 edition of the Essential Guide to E-Mail Marketing.)