Summary
Setting up DMARC (Domain-based Message Authentication, Reporting, and Conformance) when you use multiple email senders for the same domain is not only possible but highly recommended for robust email security and deliverability. The core principle involves ensuring all legitimate sending sources are properly authenticated with SPF and DKIM, and that your DMARC record is configured to monitor and then enforce policies based on these authentication results. The process typically begins with a monitoring-only policy to identify all valid email streams before moving to more restrictive policies.
Key findings
- Feasibility: It is entirely possible to implement DMARC successfully even when using multiple email service providers (ESPs) or systems for different email types (e.g., transactional, marketing, shipping, review requests) under a single domain.
- Single DMARC Record: A single domain can only have one DMARC record. This record should be placed at _dmarc.yourdomain.com in your DNS.
- Phased Implementation: The recommended approach is a gradual rollout, starting with a p=none policy (reporting only) to gather data on all sending sources before moving to p=quarantine and finally p=reject. This strategy helps avoid unintended deliverability issues.
- Subdomain Policy: Ensure your DMARC record also accounts for subdomains, often by setting sp=none initially to include them in the monitoring process.
Key considerations
- Comprehensive Inventory: Before starting, identify all legitimate services or third-party senders that are authorized to send email on behalf of your domain. This includes marketing platforms, transactional email services, and any internal systems.
- Authentication Setup: Each sending service must have proper SPF and DKIM records configured and aligned with your domain. This is crucial for DMARC to pass.
- Reporting Analysis: Actively monitor DMARC reports (RUA and RUF) to detect any legitimate email streams that are failing authentication or alignment. These reports help in identifying unauthorized senders and misconfigurations.
- Policy Enforcement: Only transition to stricter policies like p=quarantine or p=reject once you are confident that all your legitimate email traffic passes DMARC validation. For detailed guidance, review our article on safely implementing DMARC p=reject.
What email marketers say
Email marketers, especially those new to deliverability, often find DMARC intimidating due to its technical nature and the involvement of multiple sending platforms. However, they generally agree that while challenging, it's a necessary step for email security and brand protection. Their experiences highlight the importance of starting cautiously and methodically, often relying on expert advice to navigate the complexities.
Key opinions
- Initial Confusion: Many marketers, particularly those new to email authentication, admit to not fully understanding DMARC, especially when multiple senders are involved. They seek clear, step-by-step guidance.
- Complexity: The setup can seem daunting, even described as “6-hour-bootcamp-complicated,” indicating a steep learning curve for those without a technical background.
- Seeking Guidance: There's a strong desire for practical explanations and real-world examples to demystify the process.
- Deliverability Weakness: Some marketers identify deliverability and backend configurations as their personal weaknesses, highlighting the need for user-friendly solutions and educational resources.
Key considerations
- Holistic View: Marketers must understand that DMARC covers all email sent from their domain, regardless of the sender. This means all email streams (transactional, marketing, etc.) must be identified and properly authenticated.
- Third-Party Senders: When using multiple third-party senders, ensuring each one correctly configures SPF and DKIM for your domain is paramount. They should provide you with the necessary DNS records to add. This also relates to setting up email authentication for multiple ESPs.
- Alignment Requirements: DMARC requires either SPF or DKIM to align with the From: domain. Marketers need to verify that their ESPs support this alignment for all email types.
- Monitoring Tools: Leveraging DMARC reporting tools is essential to gain visibility into email streams, identify authentication failures, and ensure that all legitimate email is passing. Insights from these tools help prevent emails from landing on a blacklist or blocklist due to misconfigurations.
Marketer view
Email marketer from Email Geeks asks about setting up DMARC for a single domain with multiple sending companies for various email types like transactional, shipping, marketing, and review requests. They are unsure if DMARC is possible in such a situation and what a good starting point would be.
Marketer view
Email marketer from Spiceworks Community emphasizes the challenge of configuring DKIM and DMARC correctly when third-party senders are involved, noting that these external services often 'spoof' the domain. This highlights the need for precise setup to maintain deliverability.
What the experts say
Email deliverability experts concur that DMARC implementation with multiple senders is not only feasible but a critical best practice. They stress a methodical, phased approach, starting with monitoring to identify and resolve any authentication gaps. Experts highlight the importance of understanding alignment and conducting a thorough inventory of all sending sources to ensure a smooth transition to stricter DMARC policies without disrupting legitimate email flow. They often suggest external resources or boot camps for comprehensive learning.
Key opinions
- It's Possible: Experts confirm that DMARC can indeed be set up for a single domain even with numerous different companies sending emails for various purposes.
- Phased Approach is Key: The standard phased rollout—starting with p=none, then p=quarantine, and finally p=reject—is universally recommended to manage risk.
- Subdomain Inclusion: Advise including subdomains in the initial monitoring phase (using sp=none) to ensure comprehensive coverage.
- No Downside to Reporting Mode: There is no known risk or downside to starting with a reporting-only DMARC policy (p=none), making it a safe first step for all organizations.
Key considerations
- Identify 'Holes': This involves proactively finding legitimate email streams that are not yet authenticated, or where email is sent without proper DMARC alignment, particularly from third-party partners sending on your behalf. This is crucial for verifying SPF, DKIM, and DMARC setup.
- Full Inventory: Conduct a comprehensive inventory of all email sending sources within your company to identify all authentication issues and define appropriate policies for each.
- Vendor Configuration: Work closely with each of your four (or more) email sending companies to ensure they correctly implement SPF and DKIM records for your domain and ensure DMARC alignment. This is a common challenge that requires diligence.
- Educational Resources: For those new to DMARC, resources like boot camps or detailed guides can provide the necessary in-depth understanding. The Global Cyber Alliance often offers educational programs that can be invaluable in navigating the complexities of DMARC implementation, as highlighted by industry experts.
Expert view
Deliverability expert from Email Geeks confirms that DMARC is indeed possible to set up even with multiple email senders. They outline the standard implementation steps: start with a 'none' policy, identify and fix issues, then progress to 'quarantine' and 'reject', with continuous monitoring.
Expert view
Deliverability expert from Word to the Wise advises that achieving DMARC alignment for multiple senders requires careful coordination. Each third-party vendor must properly authenticate emails using SPF and DKIM on behalf of your domain for DMARC to pass.
What the documentation says
Official documentation and technical guides consistently reiterate that DMARC is designed to handle complex email environments, including those with multiple sending sources for a single domain. The key is proper DNS record configuration for SPF and DKIM on each sending platform, ensuring all legitimate traffic aligns with the DMARC policy. Documentation also emphasizes the necessity of a single DMARC record per domain and the iterative process of policy enforcement.
Key findings
- One DMARC Record: RFC 7489, which defines DMARC, states unequivocally that a domain should publish only one DMARC record at the _dmarc subdomain. Having multiple records will invalidate the configuration.
- Alignment is Key: DMARC works by checking if either SPF or DKIM (or both) pass authentication AND align with the From: domain. All senders must achieve this alignment.
- DNS Publication: The DMARC record is a TXT record published in your DNS. It instructs receiving mail servers how to handle emails that fail DMARC checks and where to send aggregate and forensic reports.
- Subdomain Handling: The sp tag within the DMARC record allows you to specify a separate policy for subdomains, providing flexibility for organizations that use subdomains for different sending purposes.
Key considerations
- SPF and DKIM for Every Sender: Each email sending platform (ESPs, marketing automation systems, transactional email services) used for your domain must have its SPF and DKIM properly configured to allow for DMARC alignment. This is foundational for setting up email authentication.
- Monitoring and Iteration: Documentation consistently advises starting with a p=none policy and incrementally moving to stronger policies (quarantine, reject) while closely monitoring DMARC reports. This mitigates the risk of blocking legitimate emails. More on DMARC policy examples here.
- Consolidated DMARC Record: If you have multiple DMARC records, you must consolidate them into a single, comprehensive record. Resources like NSLookup.io provide guidance on how to merge DMARC records effectively.
- Report Analysis: Understanding and interpreting DMARC aggregate (RUA) and forensic (RUF) reports is vital. These reports detail which emails are passing or failing authentication, providing the data needed to adjust SPF, DKIM, or DMARC configurations for each sender.
Technical article
Technical documentation from NSLookup.io clarifies that while a domain may use multiple senders, it can only have one DMARC record. This record acts as the central policy for all email sent from that domain, regardless of the source, and must be correctly configured in the DNS.
Technical article
DMARC documentation from GoDMARC Knowledge Base emphasizes that having more than one DMARC record for a single domain will break email authentication. This can lead to serious security risks and deliverability issues, reinforcing the need for a single, well-formatted record.
Related resources
11 resources
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Related pages
How to implement DMARC p=reject policy safely to avoid email deliverability issues?
How to verify DMARC, DKIM, and SPF setup?
How to set up DMARC, DKIM, and SPF for emails from a web server and manage bounce responses?
Where should SPF, DKIM, and DMARC records be placed for email authentication?
How to set up email authentication for multiple ESPs on the same sending domain?
List of DMARC tags and their meanings
Simple DMARC examples: how to start with a p=none policy
How to safely transition your DMARC policy to quarantine or reject
A simple guide to DMARC, SPF, and DKIM
Understanding and troubleshooting DMARC reports from Google and Yahoo
