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DMARC and Email Deliverability

DMARC and Email Deliverability

Email Security InsightsTechnical Guidance

DMARC and deliverability are clearly interconnected. Depending on who you ask, DMARC has either a  direct or an indirect effect, so let’s start at the beginning by defining deliverability. 

Delivery vs. Deliverability

Delivery means your email has been accepted by the endpoint, so the service that the recipient is using technically accepts your email, and that’s it. It doesn’t bother with the details of where exactly the email lands, and that’s where deliverability comes in. 

Deliverability is also commonly referred to as inbox placement. These terms relate to whether your email will reach the primary inbox of the recipient or if it will go to the “Updates,” “Spam,” or another folder that the provider might have. The concept of deliverability deals with the more refined results beyond that of the email simply being delivered to the inbox.

Does DMARC affect deliverability?

There are three groups of thought when it comes to DMARC’s effect on deliverability. The first says that DMARC simply doesn’t have any effect on deliverability—you rarely see an ISP, and most certainly not a major one, claim that if you do not have a DMARC record, your emails will not get in the inbox of your recipients.

The second group says that DMARC might have an effect on deliverability; the third claims that DMARC is the most important factor for deliverability. The truth lies somewhere between these groups because of the variety of ISPs out there.

DMARC instructs the ISP how to handle emails that fail authentication from a specific sender, but it’s up to the ISP to take action. They’re not obligated, but if they want to follow the IETF RFCs and want to be a responsible player in the ecosystem, they will do what the DMARC record instructs. 

In general, well-established ISPs in larger countries with bigger markets mind DMARC and act accordingly; however, because of the variety of ISPs, it’s hard to claim with certainty that DMARC does or does not have a direct effect on deliverability for all emails. What we can say is that the effect of having a DMARC record with a strong policy in place does indeed have an overall positive effect on deliverability. 

How does DMARC benefit deliverability?

The indirect results of implementing a good DMARC record have a positive effect on deliverability. Having valid SPF and DKIM authentication in place, with the identifiers aligned—the underpinning of DMARC—most certainly helps your emails reach inboxes. Those records help ISPs identify you as a sender and they also verify that you’re serious about your sending practices.

It is quite common for senders that do not have SPF, DKIM or both to not get their emails delivered or to have them throttled. There are many other components that factor into the decision of whether or not your emails are accepted, but authentication protocols are among the most important.

One of the other main benefits of DMARC relative to deliverability is the insight it provides into how your domain is being used. By employing dmarcian’s application to closely monitor the feedback XML reports provide, you can quickly identify the right sources and which of your email streams need adjustment for proper authentication. This tremendous benefit of DMARC is often overlooked, and senders should take advantage of everything they can (especially if there’s something that not only helps email deliverability, but also the overall security and digital presence of their organization).

DMARC is no remedy for poor content and bad lists

When you have DMARC deployed with an enforcement policy of p=quarantine or p=reject, you’re protecting your domain from spoofing and phishing as well as helping to prevent your outgoing email being marked as spam.

If spammers send forged messages using your organization’s name or domain, people who get these messages might report them as spam. This means legitimate messages from your organization might also be marked as spam. Over time, your organization’s internet reputation can be negatively affected.


DMARC, SPF and DKIM are protocols that improve deliverability and reduce spam liability, but the content of the email and well-managed email lists also have an effect.

Having your messages reported as spam has a consequential influence on deliverability. If you’re sending emails to several people at the same ISP, if just one person marks your email as spam, your emails will either get throttled or will directly start hitting the spam folder for most of the other recipients at that ISP.

Having poorly maintained lists also can affect deliverability, as it could result in your sending to a spam trap. There are many types of spam traps, but the one that legitimate senders deal with the most is a recycled spam trap. It is when an email address that was previously used by someone is repurposed into a spam trap after a period of inactivity. After the email stops being used, a timer kicks in; depending on the ISP, the interval can be from between 3 and 12 months, with most companies being between around 6 to 8 months. After a certain point, the email address will start sending bounces to warn legitimate senders and tell them, “Hey, this address isn’t used any longer; stop sending to it.” 

After sending bounces for a period of time, the ISP will stop sending them but will resume accepting emails for this address—this is where the “spam trap” part officially kicks in. If you’re a marketing company that has been sending emails to this address, and you neglected to remove it from your list when the ISP was sending bounces, then your emails to this ISP may be sent directly to the spam folder or get rejected outright.

How to improve deliverability

In closing, here are some steps you can employ to improve your email deliverability:

  • Maintain your email lists regularly and effectively. Make sure to monitor your statistics daily, especially the open and click rates, which is the easiest indicator whether someone wants to keep receiving your content, and take appropriate actions.
  • Adopting COI/DOI (confirmed/double opt-in), which requires your subscribers to click on a link in a confirmation email before you start sending them marketing content.
  • Utilize segmentation by ensuring you’re differentiating your content based on as many criteria as it makes sense for your business.
  • In general, follow best practices for email marketing so your content is consumed and acted upon.   

And importantly, deploy and maintain a solid DMARC record. As we’ve established, the direct and indirect benefits of implementing a “p=reject” DMARC policy (stronger DNS-based authentication, aligned identifiers, unique domain-use feedback, brand protection and awareness, and many more) most definitely help not only your deliverability, but also the overall digital footprint, security and presence of your organization.

Senders sometimes fail to implement a DMARC record because of their ESP. That might be because of technical constraints or simply because the ESP doesn’t feel comfortable guiding their customers through the process. Regardless of the reason, it’s crucially important to note that dmarcian’s application can assist in overcoming those challenges by providing free tools (and guidance) to ESPs, as well as to our mutual customers.

Thanks for reading and let us know if you have any questions about DMARC and deliverability.

Want to continue the conversation? Head over to the dmarcian Forum.