DMARC: The Essential Guide to Email Authentication and Security

Cyber Resilience 13th August 2024

Email has become an integral part of our daily communication, both personally and professionally. However, with the convenience of email comes the risk of cyber threats, specifically phishing attacks.

To bolster email security, organisations worldwide are increasingly adopting DMARC (Domain-based Message Authentication, Reporting, and Conformance) protocols. In this blog post, we’ll unravel the complexities of DMARC and understand its significance in ensuring a more secure email ecosystem.

What is DMARC?

DMARC is an email authentication protocol that can help protect your organisation as well as individuals from email spoofing, phishing, and other fraudulent activities. It works by allowing domain owners to set policies that instruct email receivers on how to handle emails that claim to be from their domain.

The key components of DMARC

Authentication protocols:

DMARC leverages existing email authentication protocols such as:

SPF (Sender Policy Framework): This protocol helps verify the sender’s IP address by allowing domain owners to publish a list of authorised servers that can send emails on their behalf. When a recipient’s mail server receives an email, it can check the SPF record of the sending domain to see if the sender’s IP address is authorised to send emails for that domain.

DKIM (DomainKeys Identified Mail): This protocol verifies the integrity and origin of an email by allowing email senders to digitally sign their emails with a cryptographic key. The recipient’s mail server can then verify the signature using the corresponding public key published in the domain’s DNS record. This ensures that the email content has not been tampered with in transit.

Policy setting:

Domain owners can set policies in their DMARC records to instruct email receivers on how to handle unauthenticated emails. These policies define what actions should be taken for emails that fail SPF or DKIM checks, or both. The policy options include:

  • p=none: This policy instructs receivers to take no action on unauthenticated emails but to send reports to the domain owner for monitoring purposes.
  • p=quarantine: This policy instructs receivers to quarantine unauthenticated emails, typically placing them in the recipient’s spam or junk folder.
  • p=reject: This policy instructs receivers to reject unauthenticated emails entirely, preventing them from reaching the recipient’s inbox.

Reporting mechanism

DMARC provides valuable feedback to domain owners through two types of reports:

Aggregate Reports: These reports offer summarised data on email authentication results, such as the number of emails received, the number that passed or failed authentication, and the sources of the emails. This information helps domain owners understand the overall effectiveness of their DMARC policy and identify any potential issues.

Forensic Reports: These reports provide more detailed information on individual emails, including the sender’s address, the recipient’s address, the authentication results for SPF and DKIM, and the message content. This information can help investigate suspicious email activity and identify phishing attempts.

The benefits of DMARC implementation

Phishing prevention:

DMARC helps prevent phishing attacks by blocking unauthorised emails that claim to be from a specific domain. Phishing emails often try to trick recipients into revealing personal information or clicking on malicious links.

By implementing DMARC and setting a rejection or quarantine policy for unauthenticated emails, your organisation can significantly reduce the number of these deceptive emails reaching customers or employees. This helps to protect them from falling victim to phishing scams.

Brand protection:

You can protect your organisation’s brand reputation by implementing DMARC. When recipients can trust the source of communication they receive, it strengthens their brand image. DMARC achieves this by authenticating your emails, ensuring that only authorised emails appear to be from your domain.

This reduces the risk of malicious actors impersonating your organisation for fraudulent purposes, such as sending spam or conducting business email compromise (BEC) attacks.

Enhanced email deliverability:

DMARC improves email deliverability by reducing the chances of legitimate emails being marked as spam. Spam filters often rely on a variety of factors to identify and block spam emails.

By implementing DMARC and establishing a clear authentication mechanism for your emails, you can increase the likelihood that legitimate emails from your organisation will bypass spam filters and reach the intended recipients’ inboxes. This ensures important communication from your organisation is delivered effectively.

Challenges and considerations

  • Gradual Implementation: Organisations often implement DMARC gradually, starting with a “p=none” policy to monitor email authentication results. This allows them to fine-tune their configuration before moving to stricter policies.
  • Third-party services: Organisations using third-party email services need to ensure these services are aligned with DMARC policies. It’s essential to work closely with service providers to avoid disruptions to email communication.

How can Net Defence help?

DMARC plays a pivotal role in fortifying email security and can protect your organisation from the ever-evolving landscape of cyber threats. By implementing DMARC protocols, your business can bolster its defences, instil trust among recipients, and contribute to a more secure and reliable email ecosystem.

As cyber threats continue to evolve, embracing robust email authentication measures like DMARC is crucial in safeguarding our digital communication channels.

For more information on how Net Defence can support you with cyber security, get in touch with a member of our team today.

Further reading:

Defence, protection, security. We've got you covered.

Whether you need to enhance your approach to cyber threats, overhaul your IT infrastructure or improve your communications, we’re here to help and advise. Talk to a specialist today and take the next step towards being a stronger, more resilient business.

Speak to a specialist

Need support? Take Control.

The button below is to be used when instructed by our technical support team. This will allow a file to be downloaded to your device for them to take control and help solve the issues you are having.

ND Take Control

exe · 7.68MB

Please note: only to be used when instructed by a member of our support team. Windows devices only.