DMARC Glossary: A-Z Definitions of Key Terms

Table of Contents

Navigating the world of DMARC can feel like deciphering a foreign language. This glossary breaks down the essential terms, acronyms, and technical jargon, providing clear explanations to help you understand the ins and outs of email authentication.

A

  • Alignment: In DMARC, alignment refers to the agreement between the SPF and DKIM records for a domain. For DMARC to function correctly, the sender's SPF and DKIM records must both align with the domain's DMARC policy. If a sender has multiple SPF records or a DKIM record that doesn't match the SPF record, DMARC will not be able to verify the email's authenticity. Learn more about SPF and DKIM.

  • Authentication: The process of verifying the identity of a sender. DMARC uses SPF and DKIM to authenticate emails, ensuring they are sent from a legitimate source.

  • Authorized Sender: A domain or IP address that is explicitly permitted to send emails on behalf of a domain, as specified in the DMARC record.

B

  • BIMI (Brand Indicators for Message Identification): A standard that allows organizations to display their logo in email inboxes, enhancing brand recognition and user trust. BIMI leverages DMARC to verify the authenticity of the logo and ensure it is displayed correctly.

  • Blacklist: A list of IP addresses or domains that are known to send spam or phishing emails. Some email providers may reject emails from blacklisted senders, potentially impacting deliverability.

C

  • CNAME: A canonical name record used to redirect traffic to a different server. CNAME records are used in DMARC to configure the _dmarc record to a specific server where the policy is stored.

  • Compliance: Achieving the desired level of email authentication and security as defined by the DMARC policy. Compliance is achieved when a domain's SPF and DKIM records align with the DMARC policy and are properly configured.

D

  • DKIM (DomainKeys Identified Mail): An email authentication standard that uses cryptographic signatures to verify the sender's identity. DKIM signs emails with a private key, allowing the receiver to verify the signature using a public key associated with the domain.

  • DMARC (Domain-based Message Authentication, Reporting & Conformance): An email authentication and security protocol that uses SPF and DKIM to verify the sender's identity and enforce policies for handling unauthenticated emails. DMARC provides reporting mechanisms that help organizations track and improve their email security.

  • DMARC Policy: A set of rules that specify how to handle emails that fail DMARC authentication checks. Policies can range from "none" (no action taken) to "quarantine" (move email to spam folder) or "reject" (block the email completely).

  • DMARC Record: A DNS record that specifies the DMARC policy for a domain. The record is stored in the domain's DNS zone and is used by email servers to verify the authenticity of emails.

E

  • Email Spoofing: The act of sending emails that appear to be from a legitimate source, but are actually sent by an imposter. DMARC helps to prevent email spoofing by verifying the sender's identity and enforcing policies for handling suspicious emails.

F

  • False Positives: When DMARC incorrectly flags a legitimate email as unauthenticated. False positives can occur due to configuration errors, mismatches between SPF and DKIM records, or other factors.

  • Forensic Analysis: The process of investigating and analyzing email data to identify the source of malicious emails or spoofing attempts. Forensic analysis can help organizations track down perpetrators and take appropriate actions.

G

  • GDPR (General Data Protection Regulation): A European privacy regulation that sets rules for the collection, processing, and storage of personal data. DMARC helps organizations comply with GDPR by ensuring that email communications are authenticated and protected from unauthorized access.

H

  • Header From: The email header field that indicates the sender address. DMARC uses the "From" header field to verify the sender's identity and enforce policies.

I

  • IP Address: A unique numerical address that identifies a device or computer on a network. SPF records list the IP addresses that are authorized to send emails on behalf of a domain.

K

  • Key: A cryptographic element used in DKIM to sign emails. The private key is used to sign emails, while the public key is used to verify signatures.

L

  • Legitimate Sender: An email sender that is authorized to send emails on behalf of a domain and complies with DMARC policies.

M

  • Misalignment: When the SPF and DKIM records for a domain do not match, resulting in misaligned authentication and potential issues with DMARC verification.

  • Monitoring: The process of tracking DMARC reports and analyzing email authentication data to identify trends, detect anomalies, and improve email security.

N

  • Non-Compliance: When a domain's DMARC policy is not properly configured or implemented, resulting in a failure to authenticate emails and enforce security policies.

O

  • Open Relay: An email server that allows anyone to send emails from its domain, regardless of authorization. Open relays can be exploited by spammers and phishers to send unauthorized emails. DMARC helps prevent the abuse of open relays by enforcing email authentication policies.

P

  • Phishing: A type of cybercrime where attackers impersonate legitimate entities to trick individuals into revealing sensitive information, such as passwords or financial details. DMARC helps protect against phishing attacks by verifying the sender's identity and blocking suspicious emails.

  • Policy: A set of rules that define how to handle emails that fail DMARC authentication checks. Policies can range from "none" (no action taken) to "quarantine" (move email to spam folder) or "reject" (block the email completely).

Q

  • Quarantine: A DMARC policy that instructs email servers to move unauthenticated emails to the spam folder. Quarantine allows recipients to review suspicious emails before taking any actions.

R

  • Reporting: The process of generating and analyzing DMARC reports, which provide insights into email authentication performance and identify areas for improvement.

  • Reject: A DMARC policy that instructs email servers to block unauthenticated emails from delivery. Rejecting unauthenticated emails helps to improve email security by preventing spam and phishing attacks.

S

  • Sender ID: The domain or IP address that sends an email. DMARC uses the sender ID to verify the email's authenticity.

  • Sender Policy Framework (SPF): An email authentication standard that identifies the authorized senders for a domain. SPF records are stored in the domain's DNS zone and specify the IP addresses that are permitted to send emails on behalf of the domain.

  • Spoofing: The act of sending emails that appear to be from a legitimate source, but are actually sent by an imposter. DMARC helps to prevent email spoofing by verifying the sender's identity and enforcing policies for handling suspicious emails.

  • Spam: Unsolicited bulk emails, often containing promotional content or phishing scams. DMARC helps to reduce spam by verifying the sender's identity and blocking unauthenticated emails.

T

  • TXT Record: A DNS record that stores text-based information, such as DMARC policies, SPF records, and DKIM keys.

U

  • Unauthenticated Email: An email that fails DMARC authentication checks, indicating that the sender's identity cannot be verified. DMARC policies determine how to handle unauthenticated emails.

V

  • Verification: The process of checking the authenticity of an email using DMARC, SPF, and DKIM. Verification ensures that the sender is legitimate and that the email has not been tampered with.

W

  • Whitelisting: A process of adding trusted senders to a list of authorized senders, ensuring that their emails are not blocked by DMARC policies. Whitelisting can be used for trusted partners, internal senders, or other known sources.

X

  • X-DMARC-Result: A header field added to emails that indicates the result of DMARC verification. The header field provides information about the email's authentication status and whether it passed or failed DMARC checks.

Y

  • YAML (YAML Ain't Markup Language): A human-readable data serialization language often used for storing DMARC configuration settings. YAML files provide a structured format for defining DMARC policies and other email authentication parameters.

Z

  • Zone: A section of the DNS (Domain Name System) that stores information about a domain. DMARC records, SPF records, and DKIM keys are typically stored in the domain's DNS zone.

Understanding these terms is crucial for effectively implementing DMARC and achieving the desired level of email security. Next, let's explore the various DMARC reporting options and how to interpret the data provided by DMARC reports. This will help you understand how to monitor your email security and identify potential vulnerabilities. Read more about DMARC reporting.

Definitions of Common DMARC Acronyms

Understanding the language of DMARC involves getting familiar with its unique acronyms. These abbreviations help streamline communication and simplify complex processes. Here's a breakdown of common DMARC acronyms and their meanings:

DMARC

  • Domain-based Message Authentication, Reporting & Conformance

DMARC is the primary acronym we're discussing. It represents a system that enables email senders to protect their domain from spoofing and phishing attacks. DMARC works by aligning with two other email authentication protocols: SPF and DKIM.

SPF

  • Sender Policy Framework

SPF is a system that allows domain owners to specify which mail servers are authorized to send emails on their behalf. It acts as a first line of defense against email spoofing by verifying the sender's IP address.

DKIM

  • DomainKeys Identified Mail

DKIM is a system that adds a digital signature to emails, verifying the email's origin and ensuring its contents haven't been tampered with during transit.

p=

  • Policy

The "p" parameter defines the DMARC policy for your domain. It determines what happens to emails that fail SPF and/or DKIM checks. You can choose from three main policy settings:

  • none: Emails that fail authentication checks are allowed to reach the recipient's inbox. This is the default setting for DMARC.
  • quarantine: Emails that fail authentication checks are placed in the recipient's spam or junk folder.
  • reject: Emails that fail authentication checks are rejected and never delivered to the recipient's inbox.

sp=

  • Subdomain Policy

The "sp" parameter controls the DMARC policy for subdomains of your main domain. You can use it to apply different policies to different subdomains, if needed. For example, you could use a stricter policy for your transactional emails and a more lenient policy for marketing emails.

pct=

  • Percentage

The "pct" parameter specifies the percentage of emails that will be subject to your DMARC policy. This is helpful for testing your DMARC implementation before rolling it out to all of your emails.

rua=

  • Reporting URI for Aggregate Reports

The "rua" parameter provides a URL where email service providers (ESPs) can send aggregated reports about emails sent from your domain. These reports provide insights into your email authentication performance and can help you identify and resolve any issues.

ruf=

  • Reporting URI for Forensics Reports

The "ruf" parameter provides a URL where ESPs can send forensic reports about individual emails that fail DMARC checks. These reports provide detailed information about the failed email, including its sender IP address, DKIM signature, and SPF record.

adkim=

  • Align DKIM

The "adkim" parameter specifies the alignment requirements for DKIM signatures. It can be set to "r" (relaxed) or "s" (strict). A relaxed alignment allows for different DKIM signatures, while strict alignment requires that the signing domain matches the sending domain.

aspf=

  • Align SPF

The "aspf" parameter specifies the alignment requirements for SPF records. It can also be set to "r" (relaxed) or "s" (strict). Similar to "adkim", relaxed alignment allows for different SPF records, while strict alignment requires that the sending domain matches the SPF record's domain.

Understanding the Significance of DMARC Acronyms

By understanding these acronyms, you'll gain a deeper grasp of DMARC's functionality and how it works to protect your domain. It's essential to be familiar with these terms, as they are commonly used in DMARC documentation, tools, and discussions.

Frequently Asked Questions

Frequently Asked Questions

What is DMARC and how does it work?

DMARC (Domain-based Message Authentication, Reporting & Conformance) is an email authentication protocol that helps protect your domain from email spoofing and phishing attacks. It uses SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) to verify the sender's identity and enforces policies for handling unauthenticated emails. By aligning these protocols, DMARC helps ensure that emails sent from your domain are legitimate and haven't been tampered with.

What are the different types of DMARC policies?

DMARC policies determine how email servers should handle emails that fail SPF or DKIM checks. The main policy options are: None (p=none): no actions are taken for emails that fail; Quarantine (p=quarantine): emails that fail are placed in the spam folder; and Reject (p=reject): emails are rejected outright.

What is alignment in DMARC and why is it important?

Alignment in DMARC refers to the consistency between SPF and DKIM results. It ensures that both protocols indicate the same authorized sending servers for a particular domain. Alignment strengthens the authentication process and reduces the likelihood of spoofing attacks.

How do I set up DMARC for my domain?

Setting up DMARC involves creating a DMARC record in your domain's DNS zone. This record specifies the DMARC policy for your domain and includes parameters like 'p=' for policy, 'sp=' for subdomain policy, and 'pct=' for the percentage of emails subject to the policy. You can use a phased approach, starting with a 'none' policy for monitoring and then progressively moving towards a more aggressive policy.

What are DMARC reports and how can they help me?

DMARC reports provide valuable insights into email authentication failures. They are generated by receiving email servers and contain information about emails that failed SPF or DKIM checks. Analyzing these reports helps organizations identify potential vulnerabilities, refine their policies, and improve email security.