How does a domain change affect email deliverability and what steps should be taken to prevent issues like Gmail warnings?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 Jul 2025
Updated 19 Aug 2025
8 min read
Changing a domain can feel like a simple administrative task, but for email deliverability, it introduces a complex set of challenges. What seems like a straightforward update can lead to emails landing in spam folders, or worse, being rejected entirely. Many organizations overlook the profound impact a domain change has on their email sending reputation and the critical authentication protocols that underpin it. The consequences can include frustrating warnings, like Gmail's 'Be careful with this message' alerts.
When a domain is changed, you're essentially starting over in the eyes of mailbox providers. They rely heavily on a domain's history and behavior to determine whether emails from it are legitimate. A new or abruptly changed domain lacks this established trust, immediately raising red flags. This can lead to significant drops in inbox placement, impacting everything from transactional emails to marketing campaigns. The good news is that with proper planning and execution, many of these issues can be avoided or quickly mitigated.
I'll delve into why domain changes affect email deliverability, the technical pitfalls, and the steps you can take to prevent common issues, including those pesky Gmail warnings.
How a domain change impacts sender reputation
When you change your primary domain, it's not just the website address that needs updating. Your email infrastructure, including your sending domains and subdomains, is intricately linked to your domain's reputation. This reputation is built over time based on factors like consistent sending volume, low spam complaints, minimal bounces, and strong email authentication.
A new domain, even if it's just a slight variation of your old one, starts with a neutral reputation. It has no prior sending history, which makes it appear suspicious to mailbox providers like Gmail and Yahoo. They don't recognize it as a trusted sender, which can lead to emails being filtered into the spam folder or displaying warnings. This is particularly relevant with the new Gmail and Yahoo sender requirements for 2024, which place even greater emphasis on domain authentication and reputation.
Another common issue arises if your domain change involves a shift in web hosting or email service providers (ESPs). This can inadvertently break your email authentication records, such as SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance). If these records are not correctly migrated or reconfigured for the new domain, your emails will fail authentication checks, severely impacting deliverability and triggering warnings about potential impersonation or phishing.
Even if the new domain's links are updated within your emails, broken links from previous emails or inconsistencies between the sending domain and the linked domain can contribute to reputation issues. Mailbox providers analyze various aspects of your email, and any discrepancy can be seen as a sign of suspicious activity, leading to warnings or blocking.
Understanding the technical pitfalls
The technical foundation of email deliverability relies heavily on DNS records. When you change domains, all associated DNS records for email sending need to be updated to reflect the new domain. This includes your MX records (Mail Exchanger), which direct incoming mail, and especially your SPF, DKIM, and DMARC records.
For example, if your DKIM signature is still pointing to the old domain or its associated key, emails sent from the new domain will fail DKIM authentication. You might see a dkim=(temperror) no key for signature error in your email headers. Similarly, if your SPF record doesn't include the new sending IP addresses or domains, your SPF authentication might result in a 'neutral' or 'fail' status. Both of these are strong indicators to mailbox providers that something is amiss, often triggering Google's 'Be careful with this message' warnings.
Problematic DKIM header
Example DKIM Failuretext
dkim=(temperror) no key for signature header.i=@news.olddomain.com
This error indicates that the email's DKIM signature points to a key associated with the old domain (@news.olddomain.com), even though the email is now sent from the new domain. Mailbox providers see this mismatch and distrust the email.
Beyond authentication, any hardcoded links in email templates that refer to the old domain will break, leading to a poor user experience and further damaging your sender reputation. It's crucial that all components of your email, from the sender address to the links within the content, consistently align with your new domain.
Proactive steps to a smooth transition
Preventing deliverability issues during a domain change requires a methodical approach. It's not a task to be rushed, and careful planning is key to a smooth transition. Here are the essential steps I recommend taking:
Audit existing setup: Before anything else, fully document your current email setup, including all DNS records for SPF, DKIM, and DMARC, your email service provider (ESP) configurations, and any subdomains used for sending. This baseline is critical.
Configure new domain DNS: Set up the exact same SPF, DKIM, and DMARC records for your new domain, ensuring they align with your ESP's requirements. Double-check selector names for DKIM and all included IP addresses for SPF. A simple email deliverability test can verify proper configuration.
Warm up the new domain: Even if you're keeping your existing IP addresses, a new domain needs to build its reputation. Start by sending low volumes of highly engaged emails and gradually increase your sending volume over several weeks. This domain warming process helps mailbox providers recognize your new domain as legitimate.
Update all links and references: Ensure every link, image URL, and tracking domain within your email templates points to the new domain. This includes links in old campaigns that might still be active.
Monitor deliverability: Utilize Google Postmaster Tools and other analytics platforms to closely track your inbox placement, spam complaint rates, and authentication results for the new domain. Address any anomalies immediately. Remember, blocklist monitoring (or blacklist monitoring) is also crucial.
Pre-migration checklist
DNS Records: Verify SPF, DKIM, DMARC records for the old domain are healthy.
Email Content Audit: Identify all hardcoded links and domain references in templates.
Consider a phased rollout or parallel sending strategy. This involves sending emails from both the old and new domains for a period, gradually shifting volume to the new domain as its reputation builds. This minimizes disruption and allows you to catch any deliverability issues early.
Don't forget the email subdomains
A common mistake during domain migration is assuming that if the website is redirecting properly, email will follow suit. Email deliverability operates on a separate set of rules and configurations. One scenario I've seen play out is when the primary website domain is successfully changed, but the subdomains specifically used for email sending (e.g., mail.yourcompany.com or mg.yourcompany.com) are not updated or migrated correctly. This can leave your email sending tied to a non-existent or misconfigured old domain, leading to immediate authentication failures and reputation damage.
The key is to ensure that all email-related DNS records, especially those for SPF, DKIM, and DMARC, are correctly configured for the new primary domain and any associated sending subdomains. This often involves collaborating closely with your IT or DNS management team. If they assure you that a domain change won't affect email, it's a good idea to verify the specific DNS records yourself or with an email deliverability expert. The devil is often in the details of these technical configurations.
Ensuring a seamless email transition
Successfully navigating a domain change without damaging your email deliverability comes down to meticulous planning and thorough execution. Don't underestimate the impact a new domain can have on how mailbox providers view your emails.
By prioritizing accurate DNS record migration, carefully warming up your new domain, and continuously monitoring your sender reputation, you can ensure your emails continue to reach the inbox. Proactive measures will prevent unwelcome surprises like Gmail warnings and maintain consistent communication with your audience.
Views from the trenches
Best practices
Always update your SPF, DKIM, and DMARC records to reflect the new domain, paying close attention to subdomains.
Implement a gradual domain warming process for the new domain to build its reputation over time.
Thoroughly audit all email templates and marketing automation flows for hardcoded links or old domain references.
Use tools like Google Postmaster Tools to actively monitor your new domain's sender reputation and deliverability metrics.
Common pitfalls
Forgetting to migrate or update email sending subdomains (e.g., mail.olddomain.com to mail.newdomain.com).
Underestimating the time and effort required for a new domain to establish a good sender reputation.
Ignoring authentication errors (SPF neutral, DKIM temperror) that can trigger warnings from mailbox providers.
Assuming that a website domain change automatically handles all email deliverability configurations.
Expert tips
Set up DMARC monitoring on both your old and new domains during the transition to identify any authentication failures.
Consider a short period of parallel sending, where emails are sent from both domains, gradually increasing volume on the new one.
Communicate proactively with your email service provider about the domain change for their specific guidance and support.
Check your DMARC reports daily for insights into authentication outcomes across all mailbox providers.
Expert view
Expert from Email Geeks says a domain change absolutely impacts email deliverability and that neglecting proper authentication setup will lead to issues. It's essential to ensure all DNS records, especially SPF and DKIM, are correctly configured for the new domain and any associated subdomains to prevent impersonation warnings.
2023-11-01 - Email Geeks
Expert view
Expert from Email Geeks says Google often issues warnings when a new domain fails authentication, indicating potential impersonation. It is important to align all domains with DKIM and SPF as soon as possible after a domain change.
Gmail and 
Yahoo. They don't recognize it as a trusted sender, which can lead to emails being filtered into the spam folder or displaying warnings. This is particularly relevant with the new Gmail and Yahoo sender requirements for 2024, which place even greater emphasis on domain authentication and reputation.
Google's 'Be careful with this message' warnings.
