What is DMARC? Benefits, Implementation and How to Set It Up for Your Organization?

What is DMARC?

DMARC, short for Domain-based Message Authentication, Reporting & Conformance, is yet another email authentication protocol that is aimed at empowering the owners of specific email domains to shield their domains from being impersonated or faked, a phenomenon popularly known as email spoofing.

DMARC draws on the two established additional procedures: SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail).

It has one more security benefit because domain owners can declare policies in their DNS records explaining how messages to them that failed SPF or DKIM checks should be treated.

Also Read: What is DMARC Fail? How to Know and Fix DMARC Failure?

Since the DMARC outcomes are likely being evaluated by receiving mail servers for all arriving messages, domain owners can inform the receiver server of the actions to take on any message that fails the DMARC checks.

These actions can include merely logging it (while not doing anything with it), quarantining it, sorting it to a spam folder, or straight-up deleting it.

How does DMARC Work?

Email is Sent

When an email is sent from a domain that uses DMARC, some tests are performed by the receiving mail server to determine the actual sender’s identity.

The process begins when the email with the information needed for SPF and DKIM validation is sent from the sender’s server. These initial steps pave the way for confirming the message’s believability based on domain-specified authentication.

SPF and DKIM Checks

When the email is received, the mail server subjects it to SPF and DKIM tests. The SPF check confirms whether the email was sent from the IP address in the domain’s SPF record.

At the same time, DKIM verification checks the DKIM signature in the email header and ensures that an authorized server has signed it and that the email content has not been changed.

These checks are essential as the email’s authenticity needs to be established before it goes through the rest of the verification process.

Alignment Verification

DMARC is responsible for verifying that the domain used in the SPF and the DKIM record corresponds to the domain of the ‘From’ attribute.

This alignment verification indicates that the domain in the “From” header should strictly match or be a subdomain of the domain used during the SPF and DKIM verification processes.

This step is crucial in thwarting unauthorized senders from spoofing the email domain, thereby increasing the credibility of the whole email.

DMARC Policy Application

After alignment, the receiving mail server checks the DMARC policy set by the domain owner.

On a policy level, the server could execute no action beyond delivering the results of an authentication (None), flag the email as potentially suspicious and move it to a spam folder (Quarantine), or delete the email (Reject).

The chosen policy assists domain owners in regulating how strictly they would like to maintain email authentication and address the issue of possibly fraudulent emails.

Reporting

The receiving mail server prepares a report depending on the DMARC results and then sends it to the domain owner. It reveals the authentication results for the emails in question, specifying which ones passed or failed those checks.

This reporting mechanism is also an informative way of gauging the authentication performance of a given domain and the extent and origin of email usage associated with it to improve security measures.

Action and Feedback Loop

Domain owners analyze DMARC reports to assess email authentication or check if someone misuses their domain. From these reports, they may change their SPF or DKIM records or even their DMARC policy to improve their email protection.

This continuous feedback cycle allows domain owners to monitor and reduce email-based threat vectors and keep their domains safe from phishing and spoofing.

Benefits of DMARC

Enhanced Email Security

DMARC helps increase security simply because there is no way to spoof an email address and create phishing emails.

DMARC only allows such emails to pass the authentication checks, decreasing the recipient’s exposure to the scammers’ emails that may expose their data or funds to such fraudsters.

This improved safeguarding method is essential for all business entities that manage the customer’s data, such as banking and healthcare facilities and online shopping websites.

Improved Brand Trust

This facilitates the escalation of DMARC and protects a brand reputation by only allowing authorized mail through the organization’s domain.

This helps ensure that the supposed emails received in the organization’s name from the cybercriminals are not achieved, and hence, the brand is protected from being tainted in the eyes of the clients or partners.

If, through its adoption, businesses anticipate that an organization will better serve the members of a community, engage in reliable communication, and provide accurate information, then DMARC supports the formation of trust relationships between businesses and customers.

Greater Visibility into the Email Ecosystem

DMARC comes with a report that can assist domain owners in identifying the parties that are using the domain to send emails.

Such reports contain details such as IP addresses, originating location, and domains in corresponding/Reply-To used in emails, besides the details of the SPF/DKIM tests.

As a result, organizations can regulate their email traffic and discover who used their domain for sending messages and, if it is lawful, and based on this information, make a necessary change in their email policy.

Protection Against Phishing Attacks

Cybercrimes, especially phishing attacks, remain a problem for individuals and organizations.

Unfortunately, such an email account can easily be impersonated by a hacker, sending out emails pretending to be from the company’s domain name, for instance, to phish the employees’ login information or something to that effect.

In this way, DMARC saves the recipients from emails that contain malware or phishing emails intending to steal personal details or credentials.

This protection is essential when simple phishing email remains a serious threat, and its evolution has acquired an ever grander scale.

Reduction in Spam and Fraudulent Emails

With DMARC in the system, emails that do not pass the authentication checks may be branded as spam or blocked entirely, meaning that the rate of spam and fake emails delivered to the receivers’ mailboxes will be significantly reduced.

It not only enhances the user’s convenience but also implies that the likelihood of users being exposed to scams will be minimized.

On the same note, it supports ISPs in keeping their client email platforms clean and free, thus supporting better and more reliable email delivery.

Setting Up DMARC for Your Organization

Step 1: Set Up SPF (Sender Policy Framework)

SPF is an authentication system that can prevent unauthorized use of your domain in sending information through email by only allowing the domain holder to send emails from the IP he has authorized.

That is why you must first identify all IP addresses used to establish connections from your domain and send emails. This will include Web IP addresses for Web servers, in-house mail servers, ISP mail servers, and even third-party mail servers.

Secondly, develop an all-encompassing list that identifies all domains that send email and domains that do not (referred to as sending and non-sending domains, respectively).

Once you have collected all the required details, open a text editor that supports different encoding, such as Notepad++, Vim, or Nano then type the following statement including your SPF record:

v=spf1 ip4:1.2.3.4 ip4:2.3.4.5 ip4:x.x.x.x -all
v=spf1 ip4:1.2.3.4 ip4:2.3.4.5 include:thirdparty.com -all

Once you have established your SPF record, you must make it available on your DNS. This can be achieved by creating a new record for TXT in the DNS list with SPF written in the form of text.

If you are using BIND DNS, this can be done by using the following command:

sudo nano /etc/bind/db.yourdomain.com

Edit the zone file. Attach the following line to the last line in the zone file.

yourdomain.com. IN TXT "v=spf1 ip4:1.2.3.4 ip4:2.3.4.5 ip4:x.x.x.x -all"

Close the file and enter the below command to reload the DNS configuration.

sudo systemctl reload bind9

Last, the correct entry of the SPF record is checked using the SPF record-checking tool. The use of the following command may also be helpful:

dig +short TXT yourdomain.com

Step 2: Set Up DKIM (DomainKeys Identified Mail)

First, decide what the DKIM selector should look like; it is just a text that will be added to your domain name to help identify the DKIM public key. For example, use “standard” to create standard._domainkey.yourdomain.com.

Create a public, and private key pair for the entered domain. In the case of Windows there is a utility termed PUTTYGen which can be used.

puttygen -t rsa -b 2048 -o dkim_private_key.ppk
puttygen dkim_private_key.ppk -O public -o dkim_public_key.pub

For Linux and Mac, use the following command:

ssh-keygen -t rsa -b 2048 -C "standard._domainkey.yourdomain.com" -f dkim_private_key

After creating the key pair, one has to generate and publish a TXT record containing the public key. You can add a new TXT record through the DNS management console using the following command:

standard._domainkey.yourdomain.com. IN TXT "v=DKIM1; p=YourPublicKey"

Another thing to do is to save and reload the DNS configuration. As for DKIM, it uses public/private key cryptography to sign email messages, proving that this particular email message comes from the mentioned domain and was not changed during transmission.

Step 3: Set Up DMARC in Monitoring Mode

Ensure you have the SPF and the DKIM set up properly for your domain. Make it a policy to implement DMARC, a DNS record named _dmarc.yourdomain.com with the following text:

_dmarc.yourdomain.com. IN TXT "v=DMARC1; p=none; rua=mailto:[email protected]"

Perform a Save and Reload on the DNS configuration. There is a DMARC check tool that you can use to input the record with.

dig +short TXT _dmarc.yourdomain.com

Logging mode, also called DMARC monitoring mode, enables the recipient to get reports about the traffic without imposing any policy. This allows prospective problems to be pinpointed without directly impacting mail delivery.

Step 4: Monitor and Evaluate

For DMARC, reports should be regularly reviewed that show fraudulent messages passing through the system and legitimate messages labeled as non-legitimate. These reports reveal the number of messages and sources and the outcome of the DMARC policy.

As for the reports received by spam senders, update your SPF records with every legitimate source mentioned. Classify the senders as internal, external, or threats and engage stakeholders regarding the authenticity of the subject emails.

DMARC reports are XML files containing the message count that failed DMARC policy, DMARC policy reports, and the SPF/DKIM reports.

Step 5: Communicate and Socialize

Record the implementation policy and make it available to stakeholders. They should ensure they brief their patients and their families on their findings and treatment progression.

It should entail formulating a list and classifying all the email senders to prepare for enforcement of the manner through identification of owners for every service or sender of an email and determining all those that should be included in the SPF records as legitimate senders.

Start DMARC deployment as an internal project and have the executive team sponsor the project. Regularly communicate findings from DMARC reports and document and share the implementation policy.

Step 6: Set DMARC to Quarantine

Change DMARC policy by accessing the DNS server and finding DMARC records on your server. Deduce for the policy section by replacing “p=none” with “p=quarantine” with a message.

_dmarc.yourdomain.com. IN TXT "v=DMARC1; p=quarantine; pct=10; rua=mailto:[email protected]"

Remember to save, close, and reopen the DNS configuration. Below are some suggestions for using percentages to rank the order:

Begin with a small percentage and move up the scale to a larger one For example, one can begin with 10% and gradually progress to 100%. The quarantine mode entails that all the messages that fail the authentication process are channeled to the spam folder.

Step 7: Set DMARC to Reject

Update the DMARC policy to reject by modifying the policy statement from “p=quarantine” to “p=reject and having the following text.

_dmarc.yourdomain.com. IN TXT "v=DMARC1; p=reject; pct=100; rua=mailto:[email protected]"

Watch for acceptable emails, given the possibility that they may not be accepted. In reject mode, messages that Do not pass through DMARC are either rejected or deleted; hence, the message will not reach the recipient.

Best Practices for DMARC Implementation

Start with Monitoring

The initial step involves setting the DMARC policy to “none.” This policy lets you filter your email traffic by primarily detecting spam and other unwanted emails while delivering genuine messages to your inbox.

Most important during this phase is to gather information about the organization’s email environment and potential problems and check if SPF and DKIM records are set up properly.

Gradual Policy Enforcement

Switch from a non-blocking policy of ‘none’ to a blockading policy of ‘quarantine’ and then to a rejection policy of ‘reject’. This approach cannot be overemphasized as it aids in risk management and prevents genuine emails from being filtered.

Thus, the gradual enforcement allows time to seek a solution to any problems experienced in each phase.

Ensure Correct SPF and DKIM Configuration

However, ensure your SPF and DKIM settings are accurate before adopting DMARC. DomainKeys Identified Mail (DKIM) must be appropriately configured to sign the outgoing mail. The Sender Policy Framework (SPF) must list all the legitimate IP addresses that send mail on behalf of the domain.

Ensure that you update these records frequently to make them correspond to your current state of the email system.

Regularly Monitor and Analyze Reports

You should use the received-for-users (RUA) and received-for-forensics (RUF) reports provided by DMARC to keep track of your email traffic and the outcome of the authentication process.

These reports can be very useful in evaluating whether there are potential problems and suspicious use of your domain. Daily reports are useful and show that making changes to the DMARC policy is important.

Use a Reliable Reporting Tool

Employ a practical DMARC reporting system to select, gather, and analyze DMARC reports without manual effort. An app like DMARCian, Valimail, or any other dashboard your email service provides can simplify this process and provide some actionable results.

Conclusion

Enhance your email security with robust solutions to protect your organization’s domain from unauthorized use. Certera offers various email security solutions and verified mark certificates to ensure comprehensive protection against phishing, spoofing, and other email-based threats.

Secure your organization today with Certera and build trust with your clients through reliable email authentication.