Email authentication, fact vs fiction

The other day, I ran across a complaint on Linkedin. "Just saw another email go to the Promotions Folder with DKIM, SPF, and DMARC set up perfectly. Stop telling people this will fix their e-mail problems!" It's not the first time I've heard this, and I can understand why the author is frustrated. But, it's important not to miss the true point -- email authentication will help to improve inbox delivery. Because it does! But there's a nuanced explanation to go along with that. The devil truly is in the details.

Email authentication is fantastic. SPF and DKIM both allow you to set yourself up as YOU in the eyes of mailbox providers -- as opposed to just being one of the many clients of ESP or CRM platform X, based on a shared IP address or shared DKIM domain. This is a good thing, but it's just the start.

Setting yourself up to be identified as you means that deliverability success from this point depends on you. If you send good mail, wanted mail, you’re very likely to have deliverability success. Send unwanted email, employ bad practices, and you’re less likely to get to the inbox. In other words, email authentication helps good senders shine, and does not help bad senders escape bad practices.

Let’s re-state this in a different way: If you implement SPF and DKIM properly, you are not guaranteed inbox placement. However, if you don’t implement SPF and DKIM properly, you’re going to find it tougher to get to the inbox. Lack of email authentication truly is an impediment to deliverability success, but email authentication is NOT the only thing ISPs and mailbox providers look at when deciding where to place your mail.

DMARC does not govern inbox placement. I have never, in many years of deliverability consulting, told somebody to turn on DMARC to fix their inbox placement woes. DMARC is a good thing to have, and it indirectly helps your deliverability success by keeping bad guys away from spoofing your domain name, if configured correctly. It is NOT a magic token that guarantees inbox placement. 

DKIM does not govern inbox placement ... but. There ARE some unique scenarios, specific to certain send platforms, where fully  implementing your own DKIM domain WILL address a spam folder placement issue. Again, email authentication isn’t the only thing that mailbox providers look at -- but if you’re asking me for, what is the one thing you could do with your email authentication settings that likely COULD help with inbox placement, it’s this. Set up DKIM fully and properly, with your own custom domain.

SPF is a nice to have ... but. If you have DKIM fully in place, implementing Sender Policy Framework (SPF) with your own custom domain likely isn’t adding anything positive to a mailbox provider’s view of you. However, if you’re going to implement a restrictive DMARC policy (p=reject or p=quarantine), a customized SPF domain that "aligns with" (is part of the same domain as) your from domain helps prevent some email messages from failing DMARC, due to various weird things that can go wrong with character encoding, DNS issues, and other occasional problems. In other words, SPF alignment makes DMARC more robust, and that’s a good thing. Those edge case DMARC failures can sometimes cause spam issues, but like with other bits mentioned here, properly implementing a custom SPF domain is not going to guarantee inbox placement. That’s just not how it works.

And finally, the Gmail Promotions tab is the inbox, as far as Gmail is concerned. This is what Google wants. Google likes you and is placing your mail where they think it should be placed. It boils down to, if your email is marketing or sales oriented, Promotions tab placement isn’t wrong and you’re not going to find a solid way to avoid it. As I talked about before, you could trying everything sales-y from content -- don’t promote, and that could help. But that kind of undermines the point of the email, doesn’t it? And avoid technical solutions offered by others that claim to have "cracked the code" on how to avoid Promotions tab placement. They’re offering short term wins at best; Google constantly updates Gmail’s filtering to better fingerprint different types of messages, and you’re risking doing something that could damage your domain reputation and result in mail going to the spam folder instead. Don’t be part of that arms race.

You ultimately SHOULD set up DKIM, SPF, and DMARC properly and perfectly. It will indeed help with deliverability success. But remember the nuances I've described above, and if you need a TL;DR, it is this: Email authentication does generally help to get your emails delivered more successfully, but it's only one tiny part of the deliverability equation.



  1. “ And finally, the Gmail Promotions tab is the inbox, as far as Gmail is concerned.” Amen! As far as I’m concerned, too! 😀

  2. The problem with the Promotions tab on desktop is that the user isn't alerted that a new email is delivered.


Comments policy: Al is always right. Kidding, mostly. Be polite, please and thank you.