What can cause domain reputation to decrease and how can it be fixed?
Matthew Whittaker
Co-founder & CTO, Suped
Published 14 May 2025
Updated 19 Aug 2025
7 min read
Email deliverability relies heavily on your domain's reputation. It's the trust score mailbox providers (like Gmail and Outlook) assign to your sending domain, influencing whether your emails land in the inbox, spam folder, or are rejected entirely. When this reputation takes a hit, it can severely impact your email campaigns and communication.
I often see marketers, even those diligently warming up their domains, experience sudden drops in reputation. This can be incredibly frustrating, especially when you feel like you're doing everything right. It indicates that something has changed in how mailbox providers perceive your sending practices.
In this guide, I will break down the common causes behind a dwindling domain reputation and, more importantly, explain the practical steps you can take to diagnose and fix these issues. My aim is to help you regain trust with mailbox providers and ensure your emails reach their intended recipients.
Understanding sudden drops in domain reputation
One of the quickest ways to damage your domain reputation is through poor data quality and list management. Even if you've done a perfect domain warm-up, sending to low-quality lists, containing invalid or disengaged email addresses, will inevitably lead to problems. Mailbox providers closely monitor how recipients interact with your emails.
A primary indicator of poor list quality is a high spam complaint rate. When recipients mark your emails as spam, it's a clear signal to mailbox providers that your emails are unwanted. This directly correlates with a drop in your domain's reputation, leading to worse inbox placement for all your future sends, especially for new subscribers who lack prior engagement history with your domain. You can usually find this information in your email service provider's reports or Google Postmaster Tools.
Another major contributor to a declining reputation is sending to spam traps. These are email addresses specifically designed to catch spammers. Hitting a spam trap indicates poor list hygiene and can severely damage your reputation, potentially leading to immediate blocklisting (blacklisting) or significantly reduced inbox placement across major providers.
Checking your reputation
Google Postmaster Tools is an indispensable tool for monitoring your domain's health. The Spam Complaint Rate dashboard is a key area to check. A consistent increase in complaints will directly impact your domain's standing.
You should also explore the Compliance dashboard in Postmaster Tools. It helps ensure you meet the latest sender requirements set by mailbox providers like Google and Yahoo, which are critical for maintaining good standing and avoiding reputation penalties.
The critical role of list quality and consent
A common but often overlooked cause of low engagement and high spam complaints is assumed consent. This happens when users are added to your mailing list without explicitly opting in, such as automatically subscribing them after they accept cookies on your website. While it might seem like a quick way to grow your list, it can be incredibly detrimental to your reputation.
Recipients who didn't explicitly sign up are far less likely to engage with your emails. This leads to lower open rates, lower click-through rates, and a higher likelihood of them marking your emails as spam. Mailbox providers interpret these low engagement metrics and high complaint rates as signs of unwanted mail, which in turn degrades your domain's reputation and pushes your emails to the spam folder.
To fix this, you need to shift to a permission-based approach. For small businesses, building an engaged list requires asking for enthusiastic consent. This can be done through various channels, ensuring that every subscriber genuinely wants to receive your emails. When they expect your mail, they are more likely to open, click, and interact positively with your content.
Assumed consent
Method: Automatically adding users to a list after a passive action, like accepting website cookies.
Engagement: Typically very low, as recipients didn't explicitly ask for emails.
Spam complaints: High likelihood of recipients marking emails as spam.
Domain reputation: Negative impact, leading to poor inbox placement and potential blocklisting (blacklisting).
Explicit consent
Method: Recipients actively subscribe through forms, verbal agreement, or clear calls to action.
Engagement: Significantly higher, as subscribers expect and want your content.
Spam complaints: Much lower, as recipients are less likely to report expected emails.
Domain reputation: Positive impact, leading to improved deliverability and inbox placement.
Content, cadence, and technical foundations
Beyond list quality, how you send and what you send also play pivotal roles in your domain's reputation. The frequency (cadence) of your emails can significantly impact deliverability. Sending too many emails can lead to subscriber fatigue, resulting in increased unsubscribes and spam complaints. Conversely, sending too infrequently can cause subscribers to forget they opted in, leading to the same negative outcomes, and can also lead to engagement history with the filter going stale.
Mailbox providers also dislike unexpectedly spiky sending behavior. This can be a red flag, as compromised accounts often exhibit sudden, abnormal sending patterns. Consistency in your email volume and cadence is key to maintaining a stable and positive domain reputation.
The content of your emails is another crucial factor. Irrelevant or low-quality content won't engage your audience, leading to poor open and click rates. Using too many spam trigger words or deceptive subject lines can also cause your emails to be flagged by spam filters. Focus on providing value and relevance to your subscribers to keep them engaged.
Finally, ensuring your email authentication protocols are correctly set up is fundamental. SPF, DKIM, and DMARC records help verify your identity as a legitimate sender. Misconfigurations or missing records can lead to your emails failing authentication checks, which significantly harms your domain's reputation and can result in messages being quarantined or rejected. Being listed on a blacklist (or blocklist) is another direct consequence of poor sending practices that will obliterate your domain reputation.
Strategies for recovery and sustained health
If your domain reputation has decreased, the first step is always to identify the root cause. As discussed, this typically involves analyzing your engagement metrics, spam complaint rates, and authentication results. Once the issues are pinpointed, a strategic approach to recovery is essential.
Often, a rewarming process is necessary, especially if there has been a significant drop or a period of inactivity. This involves gradually increasing your sending volume to a highly engaged segment of your list, allowing mailbox providers to rebuild trust based on positive interactions. Simultaneously, you must commit to rigorous list hygiene, regularly cleaning out inactive subscribers and validating new addresses.
Beyond fixing the immediate problems, adopting a mindset of continuous monitoring and improvement is crucial for long-term domain health. Regular checks of your domain reputation through tools like Google Postmaster Tools, alongside proactive list management and content optimization, will help prevent future declines and ensure optimal deliverability. You can also monitor for blocklistings using a blocklist checker.
Recovery checklist
Identify Root Cause: Analyze spam complaints, bounce rates, engagement, and authentication failures via your ESP or Google Postmaster Tools.
Clean Your List: Remove unengaged subscribers, invalid addresses, and known spam traps. Implement a double opt-in process for new subscribers.
Rewarm Your Domain (if needed): Start with highly engaged segments and slowly increase volume over time.
Optimize Content: Ensure your emails are relevant, valuable, and free of spammy language or deceptive tactics.
Verify Authentication: Confirm SPF, DKIM, and DMARC records are correctly implemented and aligned.
Monitor Blocklists: Regularly check if your domain or IP is listed on any major blocklists (blacklists) and request delisting if necessary.
Sustaining a healthy domain reputation
Maintaining a strong domain reputation requires continuous vigilance and a deep understanding of email sending best practices. It's not a set-and-forget task; it's an ongoing commitment to quality, consent, and technical accuracy. Addressing the root causes, whether they stem from list quality, sending cadence, or technical misconfigurations, is paramount for recovery.
By focusing on building genuinely engaged audiences, optimizing your content for relevance, and ensuring your email authentication is robust, you can rebuild trust with mailbox providers. This proactive approach ensures your emails consistently reach the inbox, fostering better communication and stronger connections with your audience.
Views from the trenches
Best practices
Actively manage your subscriber list by regularly removing disengaged contacts to improve overall engagement metrics.
Implement a double opt-in process for all new subscribers to ensure explicit consent and higher quality leads.
Diversify your lead generation sources, using various platforms to build a more legitimate and engaged audience.
Tailor your email sending frequency to match subscriber expectations, avoiding both over-mailing and under-mailing.
Always prioritize value in your email content, ensuring it is relevant and engaging to your target audience.
Common pitfalls
Assuming consent (e.g., adding users to lists simply for accepting website cookies) often leads to low engagement.
Neglecting to monitor Google Postmaster Tools can hide critical issues like rising spam complaint rates.
Sending emails to invalid addresses or spam traps significantly damages your domain reputation and can lead to blacklisting.
Inconsistent sending volume (spiky behavior) can signal account compromise to spam filters, hurting reputation.
Over-mailing disengaged segments dilutes engagement ratios, leading to lower sender reputation over time.
Expert tips
Focus on the root cause analysis: perfect warm-ups don't fix poor data quality, bad content, or flawed targeting.
Content reputation often depreciates before the entire domain, so monitor specific campaign performance.
Spam filters are risk management systems; they really dislike unexpected spikes in sending activity.
If your domain reputation drops, it means mailbox providers didn't like what they were seeing from your sends.
Don't rely solely on automated list building; actively ask for sign-ups through various, clear calls to action.
Expert view
Expert from Email Geeks says that a rewarming of the domain will be necessary, and you need to conduct a root cause analysis to identify what caused the decline. Perfect warm-ups are ineffective if the data, content, or targeting strategy is of poor quality, as reputation is likely to decline regardless.
September 10, 2024 - Email Geeks
Expert view
Expert from Email Geeks says to check the spam complaint rate dashboard in Google Postmaster Tools first to rule that out as the source of issues. Also, remember to check the new compliance dashboard to ensure adherence to current standards.
Google Postmaster Tools is an indispensable tool for monitoring your domain's health. The Spam Complaint Rate dashboard is a key area to check. A consistent increase in complaints will directly impact your domain's standing.
