Deploying DMARC? Avoid These 7 Common Mistakes!

Today, every organization in the world is aware of the importance of Domain-based Message Authentication Reporting & Conformance, or DMARC. Not only does this email authentication protocol prevent phishers and spoofers from misusing your email domain but also helps in preserving your brand image and customer trust.

As of February 2024, there is a pivotal update for bulk email senders to be aware of. Under the new guidelines set by major tech players, it’s now mandatory for bulk email senders to rigorously follow enhanced email policies. These policies emphasize the necessity of deploying strong authentication protocols, like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC itself, to safeguard email domains more effectively. The aim is to further secure the email ecosystem against misuse and bolster the trustworthiness of email communications. This move signifies a major step in the fight against email fraud, ensuring that emails originating from a brand are authentic and reliable, thus maintaining customer trust and the integrity of the brand’s digital presence.

The global DMARC adoption rate is growing remarkably as more and more organizations are realizing the significance of securing their email domains with this email authentication protocol. According to the DMARC Industry Report 2020-2021, the number of valid DMARC policies observed in the DNS rose to a total of over 2.7 million, marking an increase of 42.9% over the course of 2020.

Even with the interest in DMARC growing exponentially, the majority of the organizations are still unable to enjoy the full benefits associated with it. As deploying DMARC can be quite a complicated process, most organizations face various challenges in properly configuring their domains’ DMARC records. So, here is a list of the seven most common problems people face while deploying DMARC and what you can do to avoid them.

#1 IGNORING PARKED DOMAINS

Every domain has both active and parked (inactive) domains. The majority of the organizations implement DMARC on their active domains while overlooking the parked ones. This is one of the gravest DMARC deployment mistakes an organization can make. Not implementing DMARC on your parked domains makes them vulnerable to misuse.

Whether active or not, these domains still represent your organization. If the hackers misuse these domains to send fraudulent emails to your customers or vendors, the reputation of your organization is threatened. For this reason, it is advisable to configure DMARC for parked domains as well. 

#2 MISCONFIGURED SPF RECORDS

The SPF record is a TXT record published in the DNS that contains a list of IP addresses of permitted senders. There are numerous ways in which you can set up an SPF record incorrectly. One of the most common and major mistakes is exceeding the 10-lookup limit in your SPF record.

Once you go over your DNS lookup limit, the domain validation or authentication may break, allowing threat actors to spoof or misuse your domain. This means that once the limit has been exceeded, every email that requires a DNS lookup won’t achieve the complete result. You may even have many emails that fail to deliver without giving you any warning.

SPF flattening offers the most effective solution to the problems caused by the SPF lookup limit. Flattening refers to the replacement of all the domains in your SPF record with their respective IP addresses. Doing this waives the need for DNS lookups. However, there are several shortcomings associated with “manual” flattening. Email service providers may modify their IP addresses without notifying you, making your SPF record inaccurate. To rectify this issue, you will have to monitor your service providers constantly and keep an eye out for these changes.

TDMARC is a DMARC deployment and monitoring software that comes with the Automatic Flattening feature, which automatically flattens your SPF record, eliminating any effort on your part.

#3 INACCURATE SPF AND DKIM ALIGNMENT

If you want your DMARC deployment to go smoothly, it is essential to understand the importance of proper SPF and DKIM alignment. The alignment of your domain’s SPF and DKIM records prevents email spoofing by:

• Matching the “header from” domain name with the “d=domain name” in the DKIM signature.
• Matching the “header from” domain name with the “MFROM” domain name used during an SPF check.

Companies often change their policy while their domain’s SPF and DKIM records are not correctly aligned, leading to low email deliverability and email spoofing. It is wise to learn everything there is to know about the proper way of aligning the SPF and DKIM records. 

#4 IMMEDIATELY SWITCHING TO THE ‘REJECT’ POLICY

Many companies go to a full ‘Reject’ policy immediately after DMARC deployment with the intention of putting a complete stop to email spoofing. However, doing this can adversely affect the email deliverability rate of your domain, preventing even the legitimate emails from landing in the receivers’ inbox. To prevent this from happening, you can deploy the policies in phases. Start with ‘None’ policy to track the traffic and identify spoofed and unsigned messages and sources. Then, switch to the ‘Quarantine’ policy gradually and keep an eye on the results. When you are sure that no legitimate emails are being redirected to spam, you can go to full ‘Reject’ policy.

#5 NOT REMEMBERING THE SUBDOMAINS

Usually, organizations completely focus on their top-level domain (eg: example.com) while deploying DMARC and overlook the security of the subdomains (eg: mail.example.com). Subdomains follow the policy set for the main domain by default. Often, domain owners focus on bringing the DMARC compliance of their main domain up to the mark and forget about doing the same for each of their subdomains. This can lead to a decreased email deliverability rate or spoofing of certain subdomains. To make sure your DMARC deployment gives great results, it is essential to put in the same amount of effort towards bringing up the compliance for the main domain as well as all the subdomains.

#6 IMPROPER DMARC SYNTAX OR CONTENT

The instructions for deploying DMARC for your email domain can be quite complicated at times. There are several things you have to keep in mind and messing up even on a single step can completely disrupt the entire process. Some common mistakes include improper syntax or formatting, wrong content and incorrect policy value. Some of the basic things that you should remember while deploying DMARC are:

• Always use “_dmarc.”
• Thoroughly check for typos
• Make sure the policy value is correct (eg: “none” is the correct value not “monitor”)
• Ensure there are no extra or missing characters
• Use a comma to separate the reporting addresses. Don’t add a space after the comma and begin the second address with MailTo:

#7 FAILING TO ANALYZE THE DMARC DATA

One of the most beneficial and important aspects of deploying DMARC is that it delivers aggregate data reports that underline your domain’s email authentication status and compliance. These reports, if analyzed properly, can offer deep and useful insights into your outbound email channel. For this reason, it is essential to figure out a way to effectively analyze and parse the data provided to you by the aggregate reports. You can do this by buying a tool and dedicating personnel solely to this task. Also, it is very important to make sure that you don’t omit a reporting address while deploying DMARC to ensure you get these reports on a regular basis.

So, these are the most common mistakes committed by organizations while deploying DMARC. Keep these in mind to ensure strengthened email domain security.

Did you face a problem while deploying DMARC? Let me know in the comments section below!

Editor’s Note: This post was originally published in 24 June 2022 and has been partially revamped and updated for accuracy and comprehensiveness.