How do Google Groups impact DMARC when forwarding emails from multiple domains?
Michael Ko
Co-founder & CEO, Suped
Published 27 May 2025
Updated 17 Aug 2025
9 min read
Dealing with DMARC (Domain-based Message Authentication, Reporting & Conformance) can be tricky, especially when you're managing email for multiple domains and utilizing Google Groups for forwarding. I've seen many organizations run into issues where legitimate forwarded emails, particularly those from a different domain within their own ecosystem, fail DMARC checks and end up in spam folders. This often happens because the act of forwarding changes aspects of the email that DMARC relies on for validation.
The core of the problem lies in how email authentication protocols like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) interact with mail forwarding. When an email is forwarded, the intermediary server (in this case, Google Groups) often modifies the message, which can invalidate the original authentication. This guide will walk you through why this happens and what steps you can take to mitigate DMARC failures when using Google Groups to forward emails from multiple domains.
DMARC is an email authentication protocol that builds on SPF and DKIM to prevent email spoofing and phishing. It allows a domain owner to publish a policy in their DNS records that tells receiving mail servers how to handle emails that claim to be from their domain but fail SPF or DKIM authentication. To pass DMARC, an email must pass either SPF or DKIM, and importantly, the authenticated domain must align with the RFC5322.From header, which is what users typically see as the sender.
SPF works by verifying the sender's IP address against a list of authorized sending IP addresses published in the sender's DNS record. When an email is forwarded, the forwarding server's IP address becomes the new sending IP, which may not be authorized in the original sender's SPF record, leading to an SPF failure. For DMARC alignment, the domain in the RFC5321.MailFrom domain (also known as the Envelope From or Return-Path) must match the RFC5322.From domain. You can learn more about these mechanisms in our guide, a simple guide to DMARC, SPF, and DKIM.
DKIM, on the other hand, involves a cryptographic signature added to the email headers. This signature is generated using a private key by the sending server and verified using a public key published in the sender's DNS. If any part of the signed email content or headers is modified during forwarding, the DKIM signature will break. DMARC requires the domain that signed the email with DKIM to align with the RFC5322.From domain. When both SPF and DKIM fail to align or authenticate, the DMARC policy (e.g., p=quarantine or p=reject) comes into play, often leading to the email being marked as spam or rejected. You can find more detail in this Google Workspace Admin Help article on email sender guidelines.
How Google Groups handle forwarded emails
Google Groups can act as mailing lists or aliases, distributing incoming emails to multiple members. When an email is sent to a Google Group, the group's server often takes ownership of the email for redistribution. This process, while seemingly simple, can introduce DMARC complications, especially if the original sender's domain has a DMARC policy of p=quarantine or p=reject. The issue is further compounded when you're forwarding emails from multiple domains through these groups.
When Google Groups forwards an email, it often modifies the email headers or body, which can invalidate the original DKIM signature. Moreover, the SPF check will now see Google's sending IP, which is unlikely to be authorized by the original sender's SPF record. This dual failure can cause the email to fail DMARC. In some cases, Google Groups may rewrite the From header to include a via tag or even completely replace the From address with the group's address, which can help DMARC pass for the group, but obscures the original sender. This is a common challenge with email forwarding services, as detailed in this Postmark article on how forwarding breaks DMARC. It's worth exploring how email forwarding affects SPF, DKIM, and DMARC validation in more detail.
When you have a primary domain and a shortened domain, both within Google Workspace, and emails are forwarded from the marketing domain's Google Group to employee inboxes on the shortened domain, the system needs to maintain authentication. The challenge is that when an employee forwards an email from their shortened domain address, it's the authentication of the *original* marketing domain that needs to be preserved, not just the shortened domain's. If the original DMARC policy for the marketing domain is strict, this often leads to deliverability issues.
Direct email sending
SPF validation: The sending IP is typically authorized by the domain's SPF record, resulting in a pass.
DKIM validation: The email is signed by the legitimate sender, maintaining the signature's integrity.
DMARC alignment: Both SPF and DKIM domains typically align with the RFC5322.From domain, leading to a DMARC pass.
Google group forwarding
SPF failure: The forwarding server's IP often doesn't match the original domain's SPF record, causing SPF to fail.
DKIM breakage: Email content or header modifications by the group can invalidate the DKIM signature.
DMARC failure: If both SPF and DKIM fail authentication or alignment, the DMARC policy (e.g., p=quarantine) can lead to messages being rejected or sent to spam.
Mitigating DMARC failures with multiple domains
One of the most effective ways to combat DMARC failures due to forwarding is through ARC (Authenticated Received Chain). ARC is a protocol that allows forwarding mail servers to preserve the original email authentication results, even if the message is modified. It essentially creates a chain of trust that mail servers can follow to verify the legitimacy of a forwarded email. Implementing ARC is crucial for organizations that rely on forwarding, as it helps recipient servers understand that the email, despite changes, originated from an authenticated source. Discover how to implement ARC and how it affects DMARC failures from forwarding.
For organizations using Google Workspace with multiple domains, including primary and alias domains, navigating DMARC alignment can be complex. While Google Workspace generally handles authentication well for direct sends, forwarding through Google Groups presents a unique challenge. This is particularly true for SPF alignment, as the Return-Path domain might not align with the original sender's From header. Understanding how Google Workspace handles DMARC alignment for multiple domains is essential.
To specifically address the scenario of marketing responses coming into a Google Group and then being triaged/forwarded by employees using a shortened domain, you should consider a multi-pronged approach. First, ensure both the primary marketing domain and the shortened employee domain have robust SPF and DKIM records. Second, enable ARC if your forwarding setup supports it. Third, carefully monitor your DMARC reports to identify specific instances of failures and pinpoint the cause.
Best practices for Google Groups and DMARC
DMARC policy: Start with a p=none DMARC policy while testing to avoid impacting deliverability. Monitor reports closely before moving to quarantine or reject.
ARC implementation: If Google Groups or your Workspace configuration supports ARC, ensure it is enabled to preserve authentication results across forwarding.
SPF and DKIM records: Verify that both your primary and shortened domains have correctly configured SPF and DKIM records.
Monitor DMARC reports: Regularly analyze your DMARC aggregate reports to pinpoint where and why authentication is failing for forwarded emails. Our DMARC monitoring tool can assist with this.
Advanced considerations and best practices
Rolling out a DMARC enforcement policy, like p=quarantine, requires careful planning, especially when dealing with forwarded emails. I always recommend a phased approach, starting with p=none to gather initial reports without impacting deliverability. This allows you to identify legitimate email streams that might be breaking DMARC due to forwarding or other issues. Only once you have a clear understanding of your email ecosystem should you consider moving to a stricter policy. This is further elaborated in our article on rolling out DMARC enforcement.
It's important to remember that email forwarding causing DMARC failures isn't exclusive to Google Groups. Many mailing list services and general forwarding setups can lead to similar issues. The key is that the act of re-transmitting an email from a different server often introduces changes that SPF and DKIM weren't designed to handle gracefully without protocols like ARC in place. That's why consistent DMARC monitoring is critical across all your sending domains, regardless of the forwarding service used.
Ensuring both your primary domain and any secondary domains (like your shortened employee domain) have correctly configured and aligned SPF and DKIM records is foundational. While Google Workspace handles much of this automatically for its primary services, custom forwarding setups or group aliases can still lead to unexpected authentication breaks. Regularly reviewing your DNS records and DMARC reports (including forensic reports, if available) is the best way to proactively identify and fix these issues before they impact your email deliverability or sender reputation. You can also use our blocklist checker or blocklist monitoring to ensure your domains aren't listed due to authentication failures.
Views from the trenches
Best practices
Ensure all domains, especially those used by groups or for forwarding, have strong SPF and DKIM authentication.
Consider enabling ARC if your mail infrastructure and Google Groups setup support it, as it helps preserve authentication.
Regularly review your DMARC aggregate and forensic reports to detect authentication failures related to forwarding.
Common pitfalls
Assuming that SPF and DKIM will always pass for forwarded emails, especially with strict DMARC policies.
Not accounting for Google Group's potential header modifications, which can break DKIM signatures.
Implementing a strict DMARC policy (quarantine/reject) too quickly without proper testing and monitoring.
Expert tips
If Google Groups is causing persistent DMARC issues with forwarded emails, consider using direct email routing rules in Google Workspace instead of groups for simple forwarding scenarios.
When troubleshooting, always check the full email headers of forwarded messages to understand where authentication is failing and why.
For alias domains in Google Workspace, SPF alignment can be tricky, as Google Workspace uses the main domain for the Return-Path. Focus on DKIM for alignment here.
Expert view
Expert from Email Geeks says that Google Groups can sometimes be an imperfect fit for scenarios that would be better served by simple email aliases or routing rules in Gmail admin settings, especially to avoid header rewriting issues.
2024-11-06 - Email Geeks
Expert view
Expert from Email Geeks says that if a shortened domain is a user alias domain in Google Workspace, the mail always uses the main domain in the SPF or Return-Path, meaning you don't get SPF alignment benefit on the alias itself.
2024-11-06 - Email Geeks
Navigating DMARC with forwarded emails
Managing DMARC compliance when forwarding emails through Google Groups, especially with multiple domains, requires a nuanced approach. The key challenges stem from how forwarding servers modify emails, which can break SPF and DKIM authentication. While these issues can seem daunting, solutions like ARC and diligent DMARC monitoring can significantly improve deliverability. Always prioritize understanding your email flow and authentication failures through DMARC reports before implementing strict policies.
By ensuring proper SPF and DKIM configuration for all your domains, utilizing ARC where possible, and continuously analyzing DMARC data, you can maintain strong email security and deliverability, even with complex forwarding setups involving Google Groups and multiple domains. This proactive management helps ensure your legitimate emails reach their intended recipients without being flagged as spam or rejected.
Google Groups) often modifies the message, which can invalidate the original authentication. This guide will walk you through why this happens and what steps you can take to mitigate DMARC failures when using Google Groups to forward emails from multiple domains.
