Summary
The consensus from experts, marketers, and official documentation is that DMARC is indeed compatible with shared IP addresses. DMARC authenticates emails primarily based on the domain in the 'From' header and relies on SPF and DKIM for validation. While the IP address itself is not a direct factor for DMARC's functionality, proper configuration of SPF and DKIM is crucial in shared IP environments. This includes ensuring that all legitimate senders using those shared IPs are authorized in the SPF record and/or that DKIM alignment is properly set up. Starting with a monitoring-only DMARC policy (p=none) and coordinating with your ESP are also highly recommended to ensure successful implementation and to identify and address any potential issues.
Key findings
- Domain-Based Authentication: DMARC focuses on the domain in the 'From' header, making it inherently compatible with various IP configurations, including shared IPs.
- SPF/DKIM Dependency: DMARC relies on SPF and DKIM records to authenticate email sources, and their proper configuration is essential, especially in shared IP environments.
- SPF Record Management: Effective SPF record management is critical to authorize all legitimate senders using shared IP addresses and to maintain a good sender reputation.
- Monitoring and Reporting: Continuous monitoring of DMARC reports is recommended to identify and address any authentication issues promptly.
Key considerations
- Ensure SPF Inclusion: Verify that all shared IPs used by your ESP (Email Service Provider) are properly included in your SPF record to authorize legitimate sending.
- Implement DKIM: Implement and properly configure DKIM as an additional layer of authentication, especially if SPF configuration is challenging.
- Start with Monitoring Policy: Begin with a relaxed DMARC policy (p=none) to monitor DMARC reports and assess the impact before enforcing stricter policies (p=quarantine or p=reject).
- Coordinate with ESP: Collaborate with your ESP to ensure their infrastructure is correctly configured with SPF and DKIM to support DMARC requirements.
- Monitor Sender Reputation: Be aware that in shared IP environments, the activities of other senders can affect the overall IP reputation and, consequently, your DMARC results. Therefore, closely monitor sender reputation.
What email marketers say
12 marketer opinions
DMARC can be effectively used with shared IP addresses. While DMARC authenticates emails based on the domain in the 'From' header, its successful implementation with shared IPs hinges on proper configuration of SPF and DKIM. It is crucial to ensure that the shared IPs are listed in the SPF record or that DKIM is aligned. Starting with a reporting-only (p=none) DMARC policy is advised for monitoring and assessing the impact before enforcing stricter policies.
Key opinions
- DMARC Independence: DMARC functions independently of the underlying IP infrastructure, focusing on domain-based authentication.
- SPF and DKIM Importance: Proper SPF and DKIM configuration is crucial for DMARC to function effectively with shared IPs.
- Alignment Requirements: Either SPF or DKIM needs to be aligned for DMARC to pass, with best practices suggesting both should be aligned.
- Monitoring Recommended: Starting with a reporting-only (p=none) DMARC policy is recommended to monitor DMARC reports and assess impact before enforcing stricter policies.
Key considerations
- SPF Record Inclusion: Ensure that the shared IPs used by your ESP are included in your SPF record.
- DKIM Configuration: Implement and properly configure DKIM for enhanced authentication, especially in shared IP environments.
- Policy Enforcement: Adopt an iterative approach, starting with a relaxed DMARC policy (p=none) and gradually moving towards stricter enforcement.
- Collaboration with ESP: Coordinate with your ESP to ensure their sending infrastructure aligns with DMARC requirements and best practices.
Marketer view
Marketer from Email Geeks confirms that a shared IP pool can be included in an aligned SPF record.
24 Aug 2023 - Email Geeks
Marketer view
Email marketer from Email Geeks suggests that users who implement DMARC when using an ESP with shared IP addresses should start with a reporting-only policy (p=none) to monitor DMARC reports.
3 Jun 2022 - Email Geeks
What the experts say
6 expert opinions
Experts generally agree that DMARC is compatible with shared IP addresses because it primarily authenticates emails based on the domain in the 'From' header, not the sending IP. DMARC relies on SPF and DKIM to validate email sources. While DMARC itself is IP-agnostic, careful SPF record management is crucial in shared IP environments to authorize all legitimate senders and avoid deliverability issues. Coordination with ESPs and ongoing monitoring of DMARC reports are also essential for identifying and addressing authentication problems.
Key opinions
- IP Independence: DMARC operates at the domain level and isn't inherently dependent on the type of IP address (shared or dedicated).
- SPF/DKIM Reliance: DMARC relies on SPF and DKIM to validate email sources, making their correct configuration critical.
- Shared IP Challenges: Shared IP environments require careful SPF record management to authorize all legitimate senders and avoid reputation issues due to other senders' activities.
- ESP Coordination: Working closely with your ESP is important to ensure they properly configure SPF and DKIM for their infrastructure.
Key considerations
- SPF Management: Carefully manage your SPF records to authorize all legitimate senders using the shared IPs.
- Reputation Monitoring: Monitor your sender reputation to avoid deliverability issues stemming from the actions of other senders on the shared IP.
- DMARC Reports: Monitor DMARC reports to identify and address any authentication issues promptly.
- ESP Alignment: Ensure your ESP's sending infrastructure is properly configured with SPF and DKIM to align with DMARC requirements.
Expert view
Expert from Email Geeks explains that DMARC cares about DKIM and SPF, and only one needs to be aligned.
7 Jul 2024 - Email Geeks
Expert view
Expert from Email Geeks confirms that you can have a DMARC record for any domain, regardless of the IP configuration.
21 Nov 2022 - Email Geeks
What the documentation says
4 technical articles
Official documentation confirms that DMARC is compatible with shared IP addresses. DMARC authenticates email based on the domain found in the 'From:' header and relies on SPF and DKIM for validation. While shared IPs do not inherently prevent DMARC implementation, it's crucial to ensure that shared IPs are included in the SPF record and DKIM is correctly configured. Ongoing monitoring of DMARC is recommended.
Key findings
- IP Independence: DMARC is designed to operate independently of the IP address infrastructure.
- Domain-Based Authentication: DMARC authenticates based on the domain in the 'From:' header, not the IP address.
- SPF/DKIM Reliance: DMARC relies on SPF and DKIM to validate email sources.
Key considerations
- SPF Record Inclusion: Ensure shared IPs are properly included in your SPF record.
- DKIM Configuration: Correctly configure DKIM for your domain.
- Monitoring DMARC: Regularly monitor DMARC reports to ensure proper function and identify any issues.
Technical article
Documentation from Google Workspace Admin Help explains that DMARC relies on SPF and DKIM to authenticate emails. While using shared IPs is not a direct impediment to DMARC, ensuring that the shared IPs are properly included in your SPF record and that DKIM is correctly configured is essential for DMARC to function effectively.
3 May 2025 - Google Workspace Admin Help
Technical article
Documentation from DMARC.org explains that DMARC is designed to work independently of the IP address infrastructure. DMARC focuses on the domain in the 'From:' header of an email, not the IP address from which the email was sent. Therefore, it is perfectly acceptable and common to use DMARC with shared IP addresses.
31 Dec 2022 - DMARC.org
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