Is domain authentication required for all Mailchimp senders after Gmail and Yahoo changes?
Michael Ko
Co-founder & CEO, Suped
Published 29 Jun 2025
Updated 17 Aug 2025
9 min read
The recent changes introduced by Gmail and Yahoo have certainly shifted the landscape for email senders. Many are wondering if domain authentication is now a universal requirement, particularly for those using platforms like Mailchimp who may not consider themselves bulk senders. The short answer is yes, it's highly recommended and increasingly essential for all Mailchimp users, even if you send less than 5,000 emails per day.
While the 5,000 email threshold often gets highlighted, it's not a rigid cutoff. Inbox providers can (and often do) consider lower volumes as bulk sending if they observe specific sending patterns or content. Mailchimp, as an email service provider, is aligning its requirements with these new industry standards, pushing for better email authentication practices across its user base. This proactive approach helps ensure better deliverability for everyone on their platform.
For years, email authentication has been a best practice. Now, with Gmail and Yahoo's updated requirements, it's transitioned from a recommendation to a near-mandate for anyone wanting their emails to consistently reach the inbox. Without proper authentication, your emails face a much higher risk of being rejected or sent straight to spam folders, regardless of your sending volume.
The primary authentication protocols critical for email deliverability are SPF, DKIM, and DMARC. These work together to verify that your emails are legitimate and that you, or your authorized email service provider, are indeed the sender. SPF (Sender Policy Framework) allows you to specify which mail servers are authorized to send email on behalf of your domain. DKIM (DomainKeys Identified Mail) adds a digital signature to your emails, verifying their authenticity and ensuring they haven't been tampered with in transit. Finally, DMARC (Domain-based Message Authentication, Reporting & Conformance) builds on SPF and DKIM, giving domain owners control over what happens to emails that fail authentication and providing reports on email activity.
While Mailchimp automatically applies default authentication for marketing emails sent from their own domains, the new requirements from Gmail and Yahoo emphasize the need for senders to use custom domain authentication. This means setting up your own DKIM records and publishing a DMARC record for your sending domain. If you're relying solely on Mailchimp's default authentication, your emails are much more likely to be flagged, even if you're not sending large volumes.
The reason for this shift is to combat spoofing and phishing. When you send emails using a non-authenticated domain (like a generic Gmail or Yahoo address without a custom domain), or if your domain isn't properly authenticated, it's harder for recipient inboxes to trust the sender. This makes them more susceptible to being marked as spam or blocked outright. The goal is a cleaner, safer email ecosystem, and custom domain authentication is a critical step in achieving that.
Action required for all senders
Gmail and Yahoo's latest requirements extend beyond just bulk senders. They aim to elevate the overall standard of email security. Therefore, every sender, regardless of volume, should implement SPF, DKIM, and DMARC authentication for their sending domains. Failing to do so can lead to significant deliverability issues, including emails being bounced or sent to spam. This is a crucial step to maintain a healthy sending reputation and ensure your messages reach your audience.
Mailchimp has been proactive in guiding its users through these new requirements. While they previously offered a default authentication for users who didn't set up their own domain authentication, the landscape is now different. Mailchimp strongly encourages all users to set up custom domain authentication with aligned DKIM and DMARC. This isn't just a suggestion, it's a necessary step to ensure your emails continue to land in the inbox.
Some users have reported their emails being completely blocked by Mailchimp if custom authentication is not in place. While Mailchimp has indicated they are not outright blocking sends at this moment, they are flagging accounts that may fall under the bulk sender definition and sending strong encouragement messages. The reality is, if your emails lack proper authentication, they are likely to encounter bounces and spam folder placement at the recipient end, which for all intents and purposes, means they are not being delivered effectively.
Mailchimp's stance reflects a broader industry movement towards greater email security. For instance, our article on shared domains highlights how Google and Yahoo's policies impact shared sending infrastructure. This means that while Mailchimp facilitates email sending, the responsibility for proper domain authentication ultimately rests with the user. It's a move to make all senders more accountable and improve the trustworthiness of email as a communication channel.
Mailchimp default authentication
When you send emails through Mailchimp without custom domain authentication, your emails are signed with Mailchimp's own DKIM records and sent via their shared IP addresses. While this offers a baseline level of authentication, it doesn't align the sending domain with your own brand. This can lead to your emails being flagged or filtered more aggressively by recipient servers, especially after the new Gmail and Yahoo requirements. Your brand's reputation is less directly linked to the email's authenticity.
Custom domain authentication
By setting up custom DKIM and DMARC records for your domain, you establish a direct, verifiable link between your brand and the emails sent from Mailchimp. This means your emails are signed with your domain's unique DKIM signature, and your DMARC policy dictates how recipients should handle emails that fail authentication. This significantly boosts trust signals with inbox providers, improving your domain reputation and deliverability. It also ensures better compliance with Gmail and Yahoo's requirements.
Practical steps for Mailchimp senders
Setting up custom domain authentication for your Mailchimp account involves adding specific DNS records to your domain's settings. The process for Mailchimp domain authentication typically involves configuring a DKIM record and then a DMARC record. Mailchimp provides clear instructions on the exact DNS records you need to add, which usually consist of a CNAME record for DKIM and a TXT record for DMARC. If you have direct access to your DNS settings, this setup can be quick and straightforward.
Once you've added the necessary DNS records, Mailchimp will verify them. This verification confirms that your domain is correctly set up to send authenticated emails through their platform. It's a critical step that links your brand's domain directly to the emails you send, boosting their trustworthiness and deliverability. For more guidance on integrating authentication with multiple providers, check out our guide on setting up email authentication for multiple ESPs.
Regarding domain warming after authentication, if you're authenticating an already established sending domain with existing sending history, you typically do not need to warm it up from scratch. The existing sending reputation of your domain carries over. Warming is primarily necessary for brand new sending domains or significant changes to sending infrastructure (like moving to an entirely new ESP or IP range) where there's no prior reputation established. The act of adding authentication merely improves the signals associated with your existing sending practices.
Beyond meeting compliance requirements, strong email authentication (SPF, DKIM, and DMARC) provides significant benefits for your email program. It helps improve your sender reputation, which is a key factor inbox providers use to decide whether to deliver your emails to the inbox, the spam folder, or reject them entirely. A good reputation means your emails are trusted and are less likely to trigger spam filters or end up on an email blocklist (or blacklist).
Authentication also helps prevent email spoofing, where malicious actors send emails pretending to be from your domain. DMARC, in particular, allows you to tell recipient servers what to do with emails that fail authentication. You can choose to monitor, quarantine, or even reject unauthenticated emails, significantly reducing the risk of your domain being used for phishing or other fraudulent activities. This protects your brand's integrity and your recipients' trust.
Ultimately, the stricter authentication requirements from providers like Gmail and Yahoo are a positive development for the email ecosystem. They push all senders towards better practices, creating a more secure and reliable environment for legitimate email. Even if you're not sending thousands of emails daily, embracing these standards now will safeguard your deliverability and maintain your reputation in the long run. Our comprehensive guide on email authentication delves deeper into these mechanisms.
Aspect
Unauthenticated sending
Authenticated sending
Deliverability
Higher risk of landing in spam or being rejected by inbox providers.
Navigating the complexities of email authentication and deliverability can be challenging. Here's some practical advice from the community:
Best practices
Align your DKIM with your sending domain to establish clear ownership and improve trust.
Implement a DMARC record, even with a policy of p=none, to gain visibility into your email ecosystem.
Always use a custom domain for sending rather than generic email addresses like @gmail.com or @yahoo.com.
Common pitfalls
Assuming you are not a bulk sender, even with low volumes, can lead to deliverability issues.
Relying solely on an ESP's default authentication without setting up custom DKIM and DMARC.
Ignoring the encouragement from your ESP to set up advanced authentication protocols.
Expert tips
Authenticating your domain for Mailchimp is a quick process if you have DNS access.
Mailchimp is actively flagging accounts that might be considered bulk senders and strongly encouraging authentication.
Domain warming is typically not necessary when authenticating an existing domain, only for new ones.
Expert view
Expert from Email Geeks says that authentication with a custom DKIM in Mailchimp, followed by DMARC in the DNS for the brand, works similarly for most ESPs and is the way to go.
2024-02-02 - Email Geeks
Expert view
Expert from Email Geeks says that you should be fine without warming a newly authenticated domain and that they start their clients at 5,000-10,000 emails directly.
2024-02-02 - Email Geeks
Final thoughts on Mailchimp and authentication
In summary, while the specific wording from Gmail and Yahoo targets "bulk senders" (those sending over 5,000 emails per day), the underlying principle of email authentication is now a universal expectation for reliable email delivery. For Mailchimp senders, even those with lower volumes, setting up custom domain authentication with SPF, DKIM, and DMARC is not just a recommendation, it's a critical step to ensure your emails reach your audience and avoid being caught in spam filters or blocklists (or blacklists).
Mailchimp is actively guiding its users towards this compliance, and while they may not be explicitly blocking all unauthenticated sends right now, the consequences (increased bounces, spam folder placement) are functionally the same as a block. Implementing these protocols strengthens your sender reputation, protects your brand, and ensures your email marketing efforts remain effective in an increasingly secure email environment.
