What steps should I take to resolve deliverability issues after rebranding with a new domain and ESP?
Michael Ko
Co-founder & CEO, Suped
Published 5 Jun 2025
Updated 16 Aug 2025
8 min read
Rebranding your business and migrating to a new Email Service Provider (ESP) simultaneously can feel like navigating a minefield. Many businesses discover, often too late, that their meticulously planned email campaigns are landing straight in spam folders. This scenario is far more common than you might think, and it stems from a fundamental misunderstanding of how mailbox providers (MBPs) evaluate new senders.
When you switch domains and ESPs at the same time, it's not just a technical change, it's a complete identity shift from the perspective of email filters. Your new sending domain has no established reputation, and the IPs of your new ESP, even if they're warmed for other senders, are new for your specific domain's sending patterns. This combination often triggers spam filters, leading to significant deliverability issues.
The good news is that these challenges are solvable with a structured approach. Understanding the underlying reasons for deliverability drops and implementing strategic steps can help you restore your sender reputation and ensure your emails reach the inbox.
The impact of simultaneous changes
One of the most immediate impacts of rebranding with a new domain is the complete lack of sending history for that domain. Mailbox providers, such as Gmail and Yahoo, rely heavily on historical sending patterns and recipient engagement to determine trustworthiness. When your domain is essentially new in their systems, even if the domain was registered years ago, it will be treated with extreme caution.
This lack of history, combined with a sudden shift to a new ESP (and likely new IPs), means you are starting from scratch in terms of sender reputation. It's not uncommon to see significantly lower open rates, not just due to emails landing in spam, but also because mailbox providers may not even pre-fetch images for unproven domains. This can give a false impression of lower engagement, further impacting your deliverability. When your test emails themselves are landing in spam, it's a clear indicator that the mailbox providers view you as a suspicious sender.
The simultaneous changes create a perfect storm where all the signals that MBPs use to determine legitimate sending, such as consistent sending volume, positive engagement, and a stable sending infrastructure, are reset. This leads to a cautious default behavior from filters, routing emails to the spam folder while your new identity is assessed. Understanding why your emails are going to spam is the first step toward fixing the issue.
Essential technical configurations
Before you send another email, ensure all your technical configurations are flawless. This includes SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance). These are the foundational pillars of email authentication that tell receiving servers you are who you say you are. Misconfigurations here are often a primary reason for deliverability issues, especially with a new domain.
Verify that your SPF record includes all authorized sending IPs and domains for your new ESP. Ensure your DKIM keys are correctly published as CNAME records in your DNS and that your new ESP is signing your emails with them. For DMARC, particularly if you have a p=quarantine policy, strict alignment of your From header domain with your SPF Return-Path domain or DKIM signing domain is non-negotiable. Without this alignment, even authenticated emails could be quarantined or rejected. Learn more about DMARC, SPF, and DKIM.
Here's an example of typical DNS records required for a new ESP and domain setup:
Remember, even if these records look correct, always conduct test sends to major mailbox providers and inspect the email headers to confirm that SPF, DKIM, and DMARC are passing. If you find issues like DMARC verification failures, address them immediately.
Strategic domain warming and audience re-engagement
The single most crucial step after a domain and ESP change is implementing a meticulous domain warming strategy. Without it, even perfect technical setups will result in poor inbox placement. Domain warming involves gradually increasing your sending volume to mailbox providers over time, starting with your most engaged subscribers. This slow, controlled ramp-up helps build a positive sending reputation with the new domain.
A critical part of this is re-introducing your new brand and domain to your audience. Recipients might mark your emails as spam if they don't recognize the sender, even if they previously engaged with your old brand. Consider sending a transitional email from your old domain, clearly announcing the rebrand and the new email address. This primes your subscribers for the change, reducing the likelihood of spam complaints and opt-outs. This is a core best practice for changing your domain name.
Before you even start warming, it's paramount to perform thorough list hygiene. Remove unengaged subscribers, hard bounces, and any known spam trap addresses. Sending to a clean, engaged list ensures that your initial sends generate positive signals, helping to establish trust with mailbox providers faster. This also reduces your chances of landing on a blocklist (or blacklist).
Old approach
Immediate bulk sending from a new domain/ESP.
Recipient confusion: Subscribers don't recognize the new domain, leading to spam complaints.
Lack of trust: Mailbox providers see no sending history, assume the worst, and route to spam.
Deliverability failure: High rates of emails landing in spam folders and minimal engagement.
New strategy
Phased introduction and gradual volume increase.
Pre-announcement: Send from the old domain introducing the rebrand.
Monitor engagement: Look for opens, clicks, and low complaint rates to build reputation.
Domain warming can take several weeks or even a few months, depending on your list size and sending volume. Patience and consistency are key. Trying to rush the process will almost certainly backfire, leading to more severe and prolonged deliverability issues. Consult guides on how to warm up email sending effectively.
Monitoring, analysis, and continuous improvement
Once you've addressed authentication and initiated warming, continuous monitoring is essential. Don't rely solely on open and click rates, as these can be misleading, especially during a reputation reset. Instead, focus on bounce rates, complaint rates, and direct inbox placement tests. If you're seeing low open rates and high complaint rates, it suggests a problem with recipient recognition or content quality, not necessarily a blocklist.
While checking for blocklist (or blacklist) listings is a good practice, be discerning. Many minor blocklists have little to no impact on major mailbox providers. If your emails are going to spam at Gmail, Outlook, or Yahoo, it's far more likely a domain reputation or warming issue than a listing on a niche blocklist like NoSolicitado or Hostkarma. For more insights, refer to this guide to understanding email deliverability.
Important: Checking blocklists
While checking blocklists (also known as blacklists) is a standard step, don't let it distract you from the core problem if you've recently rebranded with a new domain and ESP. Minor blocklists often have minimal impact on major mailbox providers. Focus instead on authentication, domain warming, and user engagement, which are the real drivers of overall deliverability.
True blocklist issues will typically manifest as bounce messages explicitly mentioning the listing. If you're not seeing such bounce messages, your deliverability problem is likely rooted in domain reputation and warming. For a comprehensive overview, see our guide to email blocklists.
Utilize tools like Google Postmaster Tools and your ESP's analytics to track key metrics. Pay close attention to feedback loops, which can alert you to spam complaints directly from mailbox providers. Regularly review your DMARC reports for authentication failures that might indicate underlying configuration problems or unauthorized sending. This proactive approach helps in diagnosing deliverability drops effectively.
Views from the trenches
Best practices
Start domain warming immediately with a gradual increase in sending volume to highly engaged contacts.
Send a clear announcement from your old domain to introduce the new brand and domain to prevent confusion.
Perform thorough list hygiene before sending any emails to ensure you are only mailing active, engaged subscribers.
Confirm SPF, DKIM, and DMARC records are perfectly configured and aligned for your new domain and ESP.
Monitor email metrics beyond opens and clicks, focusing on bounce rates, complaint rates, and DMARC reports.
Common pitfalls
Sending large volumes of email from a brand-new domain and ESP without a proper warming period.
Assuming blocklist listings on minor RBLs are the primary cause of deliverability issues with major providers.
Neglecting to inform subscribers about the brand and domain change, leading to higher spam complaints.
Having misconfigured email authentication records, especially with a DMARC p=quarantine policy.
Failing to clean your email list before migrating, which can introduce spam traps and unengaged contacts.
Expert tips
Your email reputation is tied to your domain and sending patterns, not just IP. A new domain is like a new identity.
If test emails go to spam, it indicates deeper domain reputation issues, not just minor blocklistings.
A `p=quarantine` DMARC policy requires impeccable SPF/DKIM alignment; otherwise, emails will be quarantined.
Consistent positive engagement is the fastest way to build trust with mailbox providers for a new domain.
Always prioritize building sender trust over rapid volume increase; patience pays off in deliverability.
Expert view
Expert from Email Geeks says that minor blocklists like NoSolicitado and Hostkarma are typically not the primary cause of deliverability issues with major mailbox providers. Significant deliverability problems are more likely due to underlying domain warming challenges.
2022-10-26 - Email Geeks
Expert view
Expert from Email Geeks explains that if test emails are consistently landing in spam, it suggests a configuration issue or that the domain is simply too new, lacking the necessary sending history to be trusted by filters.
2022-10-26 - Email Geeks
Rebuilding trust and reputation
Navigating a rebrand and ESP migration simultaneously is undoubtedly one of the most complex challenges in email deliverability. The key to overcoming these hurdles lies in recognizing that you're building a completely new sender identity from scratch. It's not just about changing a few settings, but about carefully re-establishing trust with mailbox providers and your subscribers.
By prioritizing meticulous email authentication, implementing a deliberate domain warming strategy, and maintaining open communication with your audience about the brand change, you can significantly mitigate the risks of deliverability issues. Remember to continuously monitor your performance using all available data, and be patient as your new sender reputation takes hold. These proactive steps will pave the way for successful email delivery under your new brand.
Gmail and 
Yahoo, rely heavily on historical sending patterns and recipient engagement to determine trustworthiness. When your domain is essentially new in their systems, even if the domain was registered years ago, it will be treated with extreme caution.
Gmail, Outlook, or Yahoo, it's far more likely a domain reputation or warming issue than a listing on a niche blocklist like NoSolicitado or Hostkarma. For more insights, refer to this guide to understanding email deliverability.
