What are the best resources for understanding and implementing DMARC and BIMI?
Michael Ko
Co-founder & CEO, Suped
Published 23 Apr 2025
Updated 19 Aug 2025
7 min read
Email security protocols like DMARC and BIMI are crucial for protecting your brand and ensuring your messages reach the inbox. DMARC, or Domain-based Message Authentication, Reporting, and Conformance, helps prevent email spoofing and phishing by allowing domain owners to specify how recipient mail servers should handle unauthenticated emails.
BIMI, or Brand Indicators for Message Identification, builds on DMARC by enabling organizations to display their brand logo next to their authenticated emails in supporting inboxes, enhancing trust and brand recognition. Implementing these protocols correctly is essential for modern email deliverability. Navigating their setup can be complex, but several excellent resources can guide you through the process.
I'll highlight some of the best resources for understanding and implementing both DMARC and BIMI, covering everything from foundational knowledge to practical deployment.
DMARC is the cornerstone of advanced email authentication, working alongside SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) to verify email legitimacy. Understanding how it all fits together is the first step.
I often refer to resources that break down the technical aspects into digestible chunks. For a comprehensive overview of how DMARC works and its relationship with SPF and DKIM, the Suped guide on how DMARC works offers valuable insights into its architecture and purpose. It's crucial to grasp the alignment requirements, as DMARC enforces alignment between the 'From' address and the domains authenticated by SPF or DKIM.
Setting your DMARC policy (p=none, p=quarantine, or p=reject) is a critical decision. It dictates how recipient servers should treat emails that fail authentication. For a detailed explanation of these policies and their implications, you can consult the policy modes explanation. This resource provides clarity on what happens when you move from a monitoring-only policy to one that enforces authentication.
I also recommend understanding the best practices for a DMARC setup, including organizational and subdomain policies, which are detailed in Suped's guide on DMARC setup. It emphasizes the importance of a phased approach to implementation.
Implementing DMARC
Once you have a solid understanding of DMARC's principles, the next step is practical implementation. This involves creating and publishing a DMARC DNS TXT record for your domain.
For specific instructions on how to set up DMARC, particularly for major mail providers, I find Google's Workspace Admin Help to be very straightforward. Similarly, Microsoft's documentation provides clear steps for configuring DMARC for Office 365.
A DMARC record is a TXT record added to your DNS. Here's an example of what a basic DMARC record might look like:
After publishing your record, continuous DMARC monitoring is essential. This involves analyzing the aggregate (RUA) and forensic (RUF) reports sent to the email addresses specified in your DMARC record. These reports provide insights into who is sending email on behalf of your domain, including legitimate and fraudulent sources.
Understanding and implementing BIMI
BIMI is a relatively newer standard that allows organizations to display their brand logo in the recipient's inbox, provided they have a strong DMARC enforcement policy in place. This visual cue can significantly boost brand recognition and user trust.
The official BIMI Group website is an invaluable resource for everything related to BIMI. It outlines the technical specifications, requirements, and provides updates on adoption by various mailbox providers (MBPs).
To implement BIMI, you need to have a DMARC policy set to either quarantine (p=quarantine) or reject (p=reject). This is a non-negotiable prerequisite, as BIMI relies on DMARC to ensure that the sender is legitimate. The requirements and implementation steps for BIMI are covered in detail in this Suped article about BIMI implementation.
Additionally, many mailbox providers (MBPs) require a Verified Mark Certificate (VMC) to display your logo via BIMI. A VMC verifies your logo as a registered trademark. Understanding how to set up DMARC for BIMI and the nuances of VMC implementation is key for full BIMI adoption.
Key considerations for DMARC and BIMI implementation
While DMARC and BIMI offer significant benefits, their implementation isn't always straightforward. It requires careful planning and ongoing management to ensure email deliverability and security.
One of the common challenges is identifying all legitimate sending sources for your domain to ensure they are properly authenticated. Missing even one can lead to deliverability issues when you move to an enforcing DMARC policy. This includes third-party senders like marketing platforms, transactional email services, and CRMs.
It's important to remember that these protocols, while powerful, aren't a set-it-and-forget-it solution. Ongoing monitoring of DMARC reports is crucial to adapt to changes in your email sending infrastructure and maintain a strong security posture. Transitioning your DMARC policy safely to quarantine or reject is a process that requires careful attention to avoid disruptions.
While BIMI offers visual benefits, its return on investment (ROI) needs to be considered. The primary benefit of BIMI is the enhanced brand recognition and trust it provides. For some organizations, the investment in a VMC and the ongoing management of DMARC at an enforcing policy can be substantial. You can learn more about BIMI's business value to help determine if it's the right step for your brand.
Benefits of DMARC and BIMI
Fraud Protection: DMARC significantly reduces the risk of phishing and spoofing attacks that impersonate your domain.
Enhanced Deliverability: Proper DMARC implementation helps your legitimate emails reach the inbox by building trust with mailbox providers.
Brand Recognition: BIMI allows your brand's logo to appear in supporting inboxes, increasing visibility and trust.
Improved Trust: A visible logo confirms sender legitimacy to recipients, reducing the likelihood of emails being marked as spam or ignored.
Key Considerations for Implementation
Complexity: DMARC setup requires technical understanding of DNS records and email flow.
Ongoing Management: DMARC policies need continuous monitoring and adjustment based on reports.
Cost for BIMI: Obtaining a Verified Mark Certificate (VMC) for BIMI incurs additional costs and effort.
Deliverability Impact: Incorrect DMARC policies can lead to legitimate emails being blocked or sent to spam.
Views from the trenches
Implementing DMARC and BIMI is more than just adding a DNS record. It's an ongoing process that requires continuous management and adaptation to your email sending practices. Here's some perspectives that capture the real-world experiences:
Best practices
Start with a DMARC policy of p=none (monitoring-only) to gather data before enforcing.
Use DMARC reports to identify all legitimate sending sources and ensure their authentication.
Gradually move to p=quarantine, then p=reject, monitoring the impact at each stage.
Ensure all third-party email vendors are correctly authenticating emails on your behalf.
Understand that BIMI requires a DMARC enforcing policy (quarantine or reject).
Common pitfalls
Jumping straight to a 'reject' DMARC policy without proper monitoring, leading to legitimate emails being blocked.
Failing to account for all legitimate sending sources, causing deliverability issues.
Underestimating the ongoing effort and resources needed for DMARC management and reporting.
Not validating your BIMI SVG logo and VMC, preventing it from displaying in inboxes.
Expecting BIMI to significantly improve deliverability directly, as its primary role is visual branding.
Expert tips
Consider engaging with email deliverability experts or consultants, especially if you have complex email infrastructure.
Leverage DMARC aggregate reports to gain visibility into your email ecosystem and identify non-compliant senders.
Prioritize DMARC implementation and enforcement before pursuing BIMI, as it's a prerequisite.
For BIMI, ensure your logo is trademarked and adheres to the SVG Tiny 1.2 profile for VMC compatibility.
Regularly review your DMARC reports to detect unauthorized sending or changes in email flow.
Marketer view
Marketer from Email Geeks says 250ok has good resources for how to implement DMARC and enable BIMI, and also on achieving DMARC compliance.
2020-02-28 - Email Geeks
Marketer view
Marketer from Email Geeks says BIMIGroup.org also provides valuable information.
2020-02-28 - Email Geeks
Final thoughts on DMARC and BIMI
Mastering DMARC and BIMI is an essential step towards robust email security and enhanced brand presence. By leveraging the right resources, you can confidently navigate the complexities of these protocols.
Remember, DMARC provides the foundational security layer, protecting your domain from unauthorized use and bolstering your sender reputation. BIMI then builds upon this foundation, offering a powerful visual authentication that fosters trust and strengthens your brand's image in the inbox.
The key is to approach implementation systematically, starting with monitoring, analyzing reports, and gradually moving towards stricter policies, all while ensuring your legitimate email flow remains uninterrupted. With the resources highlighted, you're well-equipped to achieve DMARC compliance and embrace the benefits of BIMI.
