Why is Senderscore reporting millions of emails being sent from my IP address when I can't account for them?
Michael Ko
Co-founder & CEO, Suped
Published 21 May 2025
Updated 15 Aug 2025
7 min read
Discovering that SenderScore reports millions of emails being sent from your dedicated IP address, when you can't account for them, can be a perplexing and alarming situation. My first thought when facing this would be whether we are truly on a dedicated IP, or if there's a misunderstanding and we're actually using a shared IP. It's a common initial reaction, especially when the volume seems so out of sync with your records.
However, even after confirming multiple times that the IP is indeed dedicated, the mystery often deepens. This scenario points to deeper issues than simple shared IP usage or email forwarding. It signals a critical need for investigation into the accuracy of the reporting and the security of your sending infrastructure.
Validating the unexpected volume
The very first step I would take is to confirm the accuracy of the SenderScore report. While SenderScore, a service provided by Validity, is a widely recognized metric for IP reputation, no single source is infallible. If your email service provider (ESP) also reports abnormal sending volumes, then it's highly likely that the observed activity is real.
Your ESP should have robust logging of all email transmission activity (MTA logs). Requesting these logs can provide concrete evidence of the actual volume of emails sent from your IP, including timestamps and recipient domains. This direct data is crucial for validating external reports and can help clarify if SenderScore is showing inaccurate data.
Additionally, I would cross-reference the SenderScore data with other reputation monitoring services. Tools like Talos Intelligence (formerly SenderBase) can offer an alternative view of your IP's sending volume and reputation. If multiple platforms indicate a significant increase in volume, then you need to treat the issue as legitimate, requiring immediate investigation into its source. This might also shed light on why your email open rates might be declining.
A crucial aspect of understanding SenderScore's volume reporting is recognizing how it gathers its data. SenderScore primarily aggregates data from mailbox providers. These providers monitor incoming email streams and contribute to the overall score and volume reporting. This means the data reflects what a broad range of receiving servers are observing from your IP. If they report millions of emails, it's because they are indeed receiving that volume.
Confirming volume reports
ESPs: Leverage your Email Service Provider (ESP) to review their internal message transfer agent (MTA) logs for the exact sending volume originating from your IP address.
If the high volume is indeed confirmed by your ESP and other reputation services, the most probable cause is a security breach or compromise. This could manifest as leaked API keys, compromised user credentials, or unauthorized access to your sending platform. Malicious actors frequently exploit such vulnerabilities to send massive amounts of spam or phishing emails from legitimate infrastructure.
The notion that the millions of emails are simply forwards is highly improbable for such a high volume. Email forwarding generally doesn't inflate SenderScore volumes to this extent. Forwarded mail is typically counted against the IP address of the forwarding server, not necessarily the original sending IP, especially when dealing with such scale. Therefore, focusing on a compromise or misconfiguration is key.
Upon suspecting a compromise, immediate action is required. This means locking down all access points. Revoking all existing API keys, changing passwords for all users with sending privileges, and reviewing user access logs for any suspicious activity are critical steps. Your ESP should be able to assist in identifying the source of unauthorized sending within their system, or if it's external, by providing detailed logs.
Compromised account
Indicators: Sudden, inexplicable spikes in sending volume, often with content you don't recognize.
Impact: Severe damage to your IP and domain reputation, leading to blocklisting (or blacklisting) and significant deliverability issues.
Action: Immediately revoke all API keys, change passwords, and investigate logs. Work with your ESP to identify and block the source.
Aggressive retries
Indicators: High soft bounce rates followed by your ESP attempting to resend emails many times.
Impact: Inflated reported volume on SenderScore, potentially harming reputation if consistently high due to poor list quality.
Action: Review bounce logs and adjust retry settings with your ESP. Clean your email lists regularly.
Understanding technical contributors
Beyond a direct compromise, significant reported volume can sometimes be attributed to technical nuances in email delivery, specifically soft bounces and aggressive retry policies by your ESP. Mailbox providers often count each retry attempt by an ESP as additional volume. So, if your emails are encountering temporary delivery issues (soft bounces) and your ESP is configured to retry sending these emails many times over an extended period, it can lead to a massively inflated volume reported by SenderScore.
While DMARC (Domain-based Message Authentication, Reporting, and Conformance) is crucial for preventing email spoofing and ensuring brand reputation, it's not directly tied to IP-level volume calculations on SenderScore. DMARC primarily concerns domain alignment for SPF and DKIM. However, a robust DMARC policy can help prevent others from misusing your domain, which in turn protects your domain's reputation, even if it doesn't directly address unexpected IP volume if the sending originates from your own infrastructure.
If aggressive retries are identified as a contributing factor, you should work with your ESP to adjust their retry parameters. Understanding why the soft bounces are occurring is also critical. It could point to issues with your mailing list quality, such as sending to outdated or invalid email addresses, or specific mailbox provider throttling. Addressing the root cause of soft bounces will reduce retry volume and improve your overall sender reputation.
Maintaining a strong sender reputation is an ongoing process. Regular monitoring of your SenderScore and other reputation metrics is essential. If you notice a sudden dip in your score or a spike in volume, it's a red flag that warrants immediate attention. Understanding why your sender score might be low will guide your response.
Beyond monitoring, proactive measures include diligent list hygiene, ensuring that you only send to engaged recipients who have explicitly opted in. High spam complaint rates and bounces are major contributors to poor IP reputation and can quickly lead to your IP being listed on a blocklist (or blacklist). Implement a strong sender authentication strategy with SPF, DKIM, and DMARC to protect your domain and IP.
In cases where unusual IP activity continues, investigating the source of emails from unrecognized IP addresses is paramount. This might involve reviewing all services connected to your domain, checking for subdomains that might be misconfigured, or even scanning for malware if your sending infrastructure is self-hosted. An in-depth guide to email blocklists can provide further context on why your IP might be listed.
Factor
Impact on reputation
Mitigation strategies
IP address reputation
Reflects sending history and behavior from a specific IP. Poor reputation leads to emails landing in spam or being blocked. Being blocklisted is a major concern.
Trustworthiness of your email domain. Influenced by spam complaints, bounces, and engagement rates. Can be more persistent than IP reputation.
Implement strong SPF, DKIM, and DMARC for authentication. Maintain healthy engagement, keep lists clean, and avoid spam traps.
Content quality
Spam trigger words, poor formatting, or excessive links can flag your emails as suspicious, regardless of IP/domain reputation.
Avoid common spam triggers. Personalize content. Ensure proper formatting. Regularly test email content with spam checkers before sending.
Next steps for a healthier email program
In conclusion, when SenderScore reports millions of unaccounted emails from your IP, it's a serious indicator that demands immediate attention. Start by verifying the data with your ESP and other tools. If confirmed, prioritize a thorough security audit for potential compromises, as this is the most likely cause. Simultaneously, review your ESP's retry settings and clean your email lists to prevent inflated volume from soft bounces. By taking these proactive and investigative steps, you can protect your sender reputation and ensure your legitimate emails reach the inbox.
Views from the trenches
Best practices
Ensure all user accounts with email sending access have strong, unique passwords and multi-factor authentication enabled.
Regularly audit API keys and user permissions, revoking any that are no longer needed or show suspicious activity patterns.
Work closely with your ESP to understand their retry policies and bounce handling. Optimize these settings to prevent excessive volume from soft bounces.
Common pitfalls
Ignoring high volume reports from SenderScore, assuming it's inaccurate or a benign anomaly.
Attributing large, inexplicable volume spikes solely to email forwarding, which typically doesn't account for millions of sends.
Neglecting to review ESP-side MTA logs, which provide definitive proof of email sending activity from your IP.
Expert tips
Implement continuous monitoring of your IP and domain reputation across multiple tools, not just SenderScore, to catch anomalies early.
Regularly scan your internal systems for malware or unauthorized scripts that could be utilizing your sending infrastructure.
Set up DMARC reporting to gain visibility into email authentication failures, which can sometimes hint at spoofing attempts using your domain.
Marketer view
A marketer from Email Geeks says to confirm that the IP address you are using is truly dedicated, as sometimes ESPs might indicate it's dedicated when it is actually shared.
2020-04-21 - Email Geeks
Expert view
An expert from Email Geeks says that DMARC is not tied to IP addresses and therefore would not be relevant to this specific issue.
Leverage your Email Service Provider (ESP) to review their internal message transfer agent (MTA) logs for the exact sending volume originating from your IP address.
Gmail recipients.
