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What is DMARC?

DMARC, known as Domain-Based Message Authentication, Reporting and Conformance, is a widely recognized standard for email authentication that helps organizations protect email domains from unauthorized use and prevent email-based cyberattacks such as spoofing and phishing, both of which are exceedingly common attack vectors that fall under the Business Email Compromise (BEC) umbrella.

UpStream email filtering not only supports DMARC authentication for outbound filtering, but can also offload the review work that your mail server would otherwise be doing for inbound filtering, expediting mail delivery and system performance. Several of its functions are also mirrored in UpStream’s Spoofing and Impersonation protection features, but these don’t defend against attackers masquerading as your organization to other people.

Secondly, if your organization doesn’t have DMARC configured, we can help with that too. Tangent offers a full consultative review of the current email security posture, provides DNS record flattening and implementation as well as ongoing monitoring to ensure no one is attempting to impersonate your organization. Anyone trying to do so will be intercepted and reported to you, with guidance on what to do from there.

While DMARC is relatively easy to implement, the investigatory, monitoring and enforcement phases of it can be very time consuming, hence why many organizations wind up not implementing it and leaving themselves vulnerable. Along with the enormous security benefits it bring, it also offers some communication benefits to organizations in terms of improved brand reputation and email deliverability.

Learn more about Tangent’s DMARC Director service here:

DMARC Director

How does DMARC work?

DMARC isn’t just one cybersecurity component: it’s the collaboration of several rules that together determine if an email message reaches a user’s inbox. The email administrator determines these sets of rules, but the two main components for inbox filtering is Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM).

SPF is a DNS TXT record that indicates the authorized email servers that can send an email on your domain’s behalf. When a recipient email server receives a message with DMARC rules enabled, it looks for the SPF record first. This DNS TXT record should have IP addresses or hostnames registered to send mail. These could be on-premise email servers, third-party servers such as those used with Google WorkSpace or Office 365 or even other sending services like SendGrid, MailChimp or Constant Contact used for marketing on an organization’s behalf.

DKIM is a little more involved than SPF. DKIM also requires a TXT record, but this record is the domain’s public key. DKIM implements asymmetric public-private key encryption. With public-private key encryption, a domain’s public key is used to encrypt a message. In the case of DMARC, a signature is encrypted with the public key published on DNS servers and verified at the recipient’s email server using the domain’s private key.

When an inbound server receives a message with DKIM, it compares the signature using the published public key with the message decrypted using a newly generated key. If the string result is the same, then the recipient’s email server can confirm that the message was not altered in any way. This also ensures that the sender is truly from the listed domain and not spoofed using a fraudulent sender address.

If the email does not match an organization’s SPF/DKIM records, it’ll be discarded, preventing attackers from masquerading as your organization and all of the damage that can bring.

What does DMARC do for me?

DMARC provides a wealth of benefits, both from the internal perspective of making spoofing and impersonation of your users much, much more difficult (sending emails to your staff as if they were other employees at the organization, particularly executives, in order to harvest information and direct them to perform tasks that further the attackers goals), as well as from the external perspective of preventing easy impersonation of your organization to people outside, such as dispatching fake invoices to your vendors or clients (the most common and unpleasant issue to then sort out with them later).

Additional scenarios that DMARC can protect against are a little further below.

Secondary, non-security benefits also mean that with a clear designation of your organization’s permitted senders, email servers are much more likely to trust messages coming from your authorized mail systems, meaning less chance of winding up in a spam folder somewhere and not being read at all, along with the protection of your ‘brand’ in that it won’t encounter the tarnish of having been impersonated and consequent negative impact on others.

Overall, DMARC is another significant component of a Defense-In-Depth strategy when it comes to inbound and outbound email deliverability and protection and well worth the time for addition.

Data Leaks

Top level executive impersonation can cause employees to send confidential company data and records to malicious parties.

Fake Invoices

Impersonation of vendors can cost your business thousands of dollars with fake invoices reaching your accounting team.

Compromised Login Credentials

Unauthorized hackers sending emails from your domain can ask clients and partners for sensitive data such as logins and passwords.

Ransomware Spreading

Through attachments and links, companies can receive emails containing ransomware, while hacked company emails can spread them to recipients including clients and staff.

Black Market Sales

Increasingly, hacked domains are being used to sell illegal goods without companies being aware.

Company Hindrance

Lawsuits, client frustration and identity theft caused by hackers with access to your email and domain can halt your otherwise successful business flow.

DMARC Support