Summary
Identifying and handling spoofed emails that violate DMARC policies requires a comprehensive approach involving proper configuration of SPF and DKIM records, publishing a DMARC record, and continuous monitoring of DMARC reports. These reports offer insights into email authentication failures and help identify the sources and nature of spoofing attempts. Analyzing these reports and leveraging tools like ARIN searches and Microsoft Defender's Threat Explorer aids in taking appropriate actions. A DMARC policy allows domain owners to instruct recipient mail servers on handling emails that fail DMARC checks, with the 'reject' policy providing the strongest protection. However, a gradual transition from 'none' to 'quarantine' to 'reject' is recommended. Common causes of DMARC failure include misconfigured records, DKIM issues, and email forwarding, which can be mitigated with SRS. Proper DMARC alignment and syntax are essential, as is alerting support and security teams if a 'reject' policy is in place. Understanding the DMARC standard (RFC7489) and utilizing DMARC reporting tools can further streamline the process.
Key findings
- Comprehensive Setup: Implementing DMARC involves setting up SPF and DKIM, publishing a DMARC record, and continuous monitoring.
- Report Analysis is Key: Analyzing DMARC reports is crucial for identifying and understanding spoofing attempts.
- Policy Options: DMARC policies allow domain owners to instruct recipient mail servers on how to handle authentication failures.
- Gradual Transition: A gradual transition to a 'reject' policy is recommended to minimize disruption.
- Alignment Matters: Proper DMARC alignment (SPF and DKIM) is essential for legitimate emails to pass authentication.
- Forwarding Issues: Email forwarding can break DMARC authentication, which can be mitigated using SRS.
Key considerations
- Record Configuration: Ensure SPF, DKIM, and DMARC records are correctly configured to prevent deliverability issues.
- Monitor Reports Regularly: Regularly monitor DMARC reports to identify potential issues and improve DMARC performance.
- Alert Support Teams: If using a 'reject' policy, alert support and security teams to anticipate related inquiries and potential intrusion attempts.
- Syntax Accuracy: Validate DMARC record syntax to prevent errors that could impact deliverability.
- Tool Utilization: Utilize available tools (e.g., DMARC reporting tools, Threat Explorer) to simplify the process.
- Address Common Failures: Address common causes of DMARC failure, such as misconfigured records, DKIM issues, and forwarding problems.
What email marketers say
10 marketer opinions
Identifying and handling spoofed emails that violate DMARC policies involves a multi-faceted approach. Key steps include setting up SPF and DKIM records correctly, publishing a DMARC record, and continuously monitoring DMARC reports. These reports help pinpoint the source of spoofing attempts, which can then be addressed by updating SPF records, fixing DKIM signatures, or adjusting the DMARC policy. Common causes of DMARC failure include misconfigured records, DKIM issues, and email forwarding. Implementing a strict 'reject' policy is advisable for enhanced security, but only after careful monitoring to avoid blocking legitimate emails. Tools like ARIN searches can help identify the owners of malicious IPs, while DMARC reporting tools simplify the monitoring process. Proper DMARC record syntax is essential, and techniques like SRS can help mitigate forwarding-related authentication issues.
Key opinions
- DMARC Setup: Implementing DMARC requires setting up SPF and DKIM records, along with publishing a DMARC record in your DNS.
- Monitoring is Crucial: Regularly monitoring DMARC reports is essential for identifying spoofing attempts and ensuring legitimate emails are properly authenticated.
- Root Cause Analysis: DMARC failures can stem from misconfigured SPF records, DKIM signing issues, or forwarding scenarios that break authentication.
- IP Identification: ARIN searches can assist in finding the owner and abuse contacts associated with IPs sending spoofed emails.
- Policy Enforcement: A strict 'reject' DMARC policy can significantly reduce phishing risks, but should be implemented cautiously.
Key considerations
- Record Accuracy: Ensure your SPF, DKIM, and DMARC records are correctly configured to avoid unintended deliverability issues.
- Forwarding Impact: Be aware that email forwarding can break DMARC authentication; consider using SRS or similar techniques to mitigate this.
- Gradual Implementation: Start with a 'p=none' DMARC policy and gradually transition to 'p=quarantine' or 'p=reject' as you gain confidence in your setup.
- Reporting Tools: Utilize DMARC reporting tools to simplify the process of monitoring and analyzing DMARC data.
- DMARC Syntax: Validate your DMARC record syntax to prevent errors that could negatively impact email deliverability.
Marketer view
Marketer from Email Geeks shares that you can run an ARIN search on the IPs sending the emails to find the owner and the abuse contacts.
12 Dec 2024 - Email Geeks
Marketer view
Email marketer from SparkPost explains that email forwarding can often break DMARC authentication, as the forwarded email may no longer align with the original sender's SPF or DKIM records. They suggest using techniques like SRS (Sender Rewriting Scheme) to mitigate this issue.
11 Jun 2025 - SparkPost
What the experts say
4 expert opinions
Effectively handling spoofed emails violating DMARC policies involves a combination of proactive measures and reactive responses. Being targeted for spoofing is often random, but having a 'reject' DMARC policy necessitates alerting support and security teams to anticipate related issues. Understanding DMARC alignment is critical for ensuring legitimate emails pass authentication checks, thereby avoiding inadvertent blockage. A gradual transition from a 'quarantine' to a 'reject' policy is recommended to minimize disruptions while strengthening protection. DMARC aggregate reports are invaluable for monitoring DMARC performance and pinpointing authentication failures, aiding in timely action against spoofing.
Key opinions
- Random Spoofing: Being targeted for domain spoofing can often be a random occurrence.
- Alignment Matters: Proper DMARC alignment (SPF and DKIM) is essential for legitimate emails to pass DMARC checks.
- Report Importance: DMARC aggregate reports provide crucial insights into DMARC performance and help identify authentication failures.
- Policy Transition: A phased approach from 'quarantine' to 'reject' is advisable when implementing DMARC policies.
Key considerations
- Support Readiness: If using a 'reject' policy, ensure your support and security teams are prepared for potential escalations and intrusion attempts.
- Monitor Reports: Regularly review DMARC reports to understand DMARC performance and identify areas for improvement.
- Transition Cautiously: Transitioning to a reject policy requires careful monitoring to prevent blocking legitimate mail.
Expert view
Expert from Word to the Wise explains the importance of DMARC alignment (SPF and DKIM alignment) to ensure legitimate emails pass DMARC checks. She explains that understanding alignment is key to preventing legitimate mail from being inadvertently blocked.
20 Jul 2023 - Word to the Wise
Expert view
Expert from Email Geeks explains it sounds like you're randomly chosen to be the spoofed domain. If your DMARC policy is set to reject, alert your support and security teams to watch for or expect an increase in help requests or intrusion attempts.
16 May 2023 - Email Geeks
What the documentation says
5 technical articles
Identifying and handling spoofed emails through DMARC involves leveraging DMARC reports for insights into email authentication failures and understanding DMARC policy options. DMARC reports aid in identifying the sources and nature of spoofing attempts, informing policy adjustments. A DMARC policy allows domain owners to instruct recipient mail servers on handling emails failing DMARC checks, with 'reject' being the strongest policy. Tools like Microsoft Defender's Threat Explorer facilitate investigating authentication results. The DMARC standard, as defined in RFC7489, provides technical specifications. Setting up DMARC records, such as in Cloudflare's DNS, requires correct syntax and values.
Key findings
- DMARC Reports: DMARC reports are essential for identifying and understanding email authentication failures and spoofing attempts.
- DMARC Policy: DMARC policies instruct recipient servers on how to handle emails failing DMARC checks.
- Reject Policy: The 'reject' policy is the strongest DMARC option, preventing unauthorized emails from reaching the inbox.
- Threat Exploration: Tools like Microsoft Defender's Threat Explorer can investigate email authentication results, including DMARC failures.
- RFC7489: RFC7489 defines the technical specifications for the DMARC standard.
- DNS Setup: Setting up a DMARC record in DNS requires correct syntax and values.
Key considerations
- Report Analysis: Analyze DMARC reports to understand the nature and origin of spoofing attempts.
- Policy Selection: Carefully select a DMARC policy (none, quarantine, reject) that aligns with your organization's risk tolerance and monitoring capabilities.
- Tool Utilization: Utilize available tools like Microsoft Defender's Threat Explorer to investigate authentication results.
- Syntax Accuracy: Ensure correct syntax and values when setting up DMARC records in DNS.
Technical article
Documentation from RFC7489 describes the DMARC (Domain-based Message Authentication, Reporting & Conformance) standard. It provides technical specifications for how email receivers should handle messages that fail authentication checks and how domain owners can receive reports on authentication results.
20 Apr 2024 - RFC Editor
Technical article
Documentation from DMARC.org explains that a DMARC policy allows domain owners to instruct recipient mail servers on how to handle emails that fail DMARC checks (none, quarantine, reject). They emphasize that the 'reject' policy is the strongest, preventing unauthorized emails from reaching the inbox.
29 Sep 2021 - DMARC.org
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