Summary
Seeing unexpected IP addresses on SenderScore for a dedicated IP is a common phenomenon in email deliverability, often indicating that mail is originating from more sources than initially perceived or that reputation systems are evaluating broader network contexts. While frequently innocuous, such occurrences typically stem from factors like email forwarding, the aggregation of data by SenderScore across larger IP blocks and associated network infrastructure, and the routing of ancillary email services-like tracking or bounce processing-through different or shared IP addresses. Furthermore, misconfigurations in DNS records, the use of multiple sending platforms, hybrid sending models, or the integration of third-party tools can introduce additional, unforeseen sending IPs. Ultimately, the appearance of an unexpected IP signifies actual mail flow from that source or a configuration issue, emphasizing the importance of comprehensive monitoring through tools like DMARC to gain full visibility into your domain's email streams.
Key findings
- Email Forwarding: A primary reason for unexpected IPs appearing on SenderScore for dedicated IPs is email forwarding. When an email is forwarded, the SPF record often breaks, and the DMARC check can fail, leading to reports that show the forwarding server's IP. This is generally innocuous.
- Network Infrastructure & Aggregation: SenderScore evaluates IP addresses not just in isolation but as part of larger IP blocks or network ranges. Unexpected IPs can appear if they are related to your network infrastructure, or if SenderScore aggregates data from closely associated sending entities within the same subnet or AS (Autonomous System).
- Ancillary Services: Even with a dedicated IP for primary email sending, other services like bounce processing, unsubscribe management, or click and open tracking can sometimes route through different, potentially shared, IPs or domains. Reputation systems may pick up activity from these associated IPs.
- Multi-Platform Sending: Organizations using multiple platforms for email sending-for example, an ESP for marketing and an in-house server for transactional emails-can see SenderScore aggregating reputation across all active sending IPs associated with the domain.
- DNS and Configuration Issues: Misconfigurations in DNS records, particularly overly permissive SPF records that include broad IP ranges, or internal routing rules, can lead to SenderScore associating your sending entity with unexpected IP addresses.
- Shared IP Pool Routing: Some Email Service Providers might route specific types of traffic, sub-account sending, or low-volume sending through shared IP pools by default, even when marketing emails use a dedicated IP. This unexpected activity can appear on SenderScore.
- Third-Party Tool Integrations: Integrating third-party tools for specific email functions, such as survey platforms, CRM email sending, or transactional email services, can introduce other sending IP addresses. If these integrations are not properly aligned, their associated IPs might appear on SenderScore.
- Cloud Infrastructure Behavior: In large cloud environments, even with dedicated IPs, underlying networks might occasionally route certain traffic or queries through different parts of expansive IP ranges, leading reputation systems to report activity from closely related or shared subnet IPs during load balancing or transitions.
Key considerations
- Leverage DMARC: Implement or review DMARC records with a monitoring policy ('p=none') to gain visibility into all mailstreams attributed to your domain, helping to identify unexpected sending sources. Gradually increase the 'pct' value and policy to enforce DMARC checks, which can also help pinpoint if forwarding is causing SPF failures.
- Understand IP Block Reputation: Recognize that SenderScore and similar reputation systems often evaluate not just individual IPs but also larger IP blocks or network ranges. An unexpected IP might appear if it's within the same subnet as your dedicated IP, or if it shares a reputation with other closely associated sending entities, especially if those IPs have a poor standing.
- Audit All Sending Services: Examine all services and platforms involved in your email ecosystem. This includes bounce processing, unsubscribe management, click and open tracking domains, CRM integrations, survey platforms, and transactional email services, as these can route through different or shared IPs and influence your overall SenderScore.
- Review DNS Configurations: Carefully inspect your DNS records, particularly overly permissive SPF records that might include broad IP ranges or multiple sending sources. Misconfigurations in internal mail routing or SMTP settings can also cause mail to originate from unintended IPs.
- Account for Hybrid Sending Models: If your organization uses a hybrid sending approach-marketing emails via a dedicated IP and transactional or system notifications via shared IP pools, in-house servers, or other services-ensure these are accounted for. Reputation systems will aggregate data across all active sending IPs associated with your domain.
- Consider IP History: If a dedicated IP was recently acquired or recycled, be aware that SenderScore might temporarily reflect historical reputation or activity from its previous owner, which could include associations with other IPs used by the prior sender.
- Validate Actual Mail Flow: If an 'unexpected' IP appears on your SenderScore report, it strongly suggests that mail is indeed originating from those other IPs, or there's a configuration issue, such as rDNS, linking them. This implies your IP might not be as isolated as you believe, or additional sending systems are in use without your full awareness.
What email marketers say
10 marketer opinions
The appearance of unexpected IP addresses on SenderScore, even for dedicated IPs, is a frequent observation for email marketers. This phenomenon often arises from email forwarding, which can alter the sending path and break SPF records. Beyond forwarding, several operational and configuration factors contribute to this. These include overly permissive SPF records, the use of multiple email sending platforms, or hybrid sending models where various email types, like transactional or system notifications, are routed through different services or shared IP pools. Furthermore, ancillary functions such as tracking domains for opens and clicks, or specific sub-account traffic, may leverage distinct, sometimes shared, IP addresses. The integration of third-party tools for functions like surveys or CRM email sending also introduces additional IPs to the domain's overall sending profile. While often harmless, the presence of these unexpected IPs underscores the need for marketers to have a comprehensive understanding of their email ecosystem, emphasizing tools like DMARC for full visibility into all mailstreams associated with their domain.
Key opinions
- Email Forwarding Impact: A common reason for unexpected IPs appearing on SenderScore is email forwarding. When an email is forwarded, the SPF record often breaks, causing the DMARC check to fail and generating reports that show the forwarding server's IP, though this is generally harmless.
- DNS Misconfigurations: Misconfigurations in DNS records, such as overly permissive SPF records that include broad IP ranges or multiple sending sources, can lead to SenderScore associating your sending entity with unexpected IP addresses.
- Multiple Sending Platforms: Organizations utilizing multiple platforms for email sending-such as an ESP for marketing and an in-house server for transactional emails-can see SenderScore aggregating reputation across all active sending IPs associated with the domain.
- Hybrid Sending Models: Unexpected IPs can appear due to a hybrid sending model where some email types, like transactional or system notifications, are routed via a shared IP pool or a different service, even when marketing emails use a dedicated IP.
- Tracking Domains & Ancillary Services: Even when the main email is sent from a dedicated IP, tracking domains for opens and clicks often utilize different IPs, which can sometimes be shared or hosted by third-party services. Reputation systems may pick up activity associated with these IPs.
- ESP Routing Decisions: Some Email Service Providers might route specific types of traffic, sub-account sending, or low-volume email through shared IP pools by default, even when a dedicated IP is primarily in use. This can lead to unexpected activity from shared IPs influencing or appearing on SenderScore.
- Third-Party Tool Integrations: Integrating third-party tools for specific email functions, such as survey platforms, CRM email sending, or other transactional email services, can introduce additional sending IP addresses. If these integrations are not properly aligned, their associated IPs might appear on SenderScore.
Key considerations
- Utilize DMARC for Visibility: Implement or review DMARC records with a monitoring policy ('p=none') to gain comprehensive visibility into all mailstreams attributed to your domain, which is crucial for identifying unexpected sending sources. Gradually increasing the 'pct' value and policy can further help in pinpointing issues, especially if forwarding causes SPF failures.
- Audit All Sending Points: Thoroughly examine all services and platforms that send email on behalf of your domain. This includes marketing ESPs, transactional email services, CRM integrations, survey platforms, and any other third-party tools, as these can introduce additional IPs to your sending profile.
- Examine DNS Records: Carefully inspect your DNS records, particularly overly permissive SPF records that might include broad IP ranges or multiple sending sources. Misconfigurations in internal mail routing or SMTP settings can also cause mail to originate from unintended IPs.
- Understand Hybrid & Ancillary Traffic: Be aware that even with a dedicated IP, certain email types like transactional or system notifications, tracking domains for opens and clicks, or low-volume sending, might utilize different or shared IP pools. These can influence your overall reputation profile and appear on SenderScore.
- Assess Innocuousness: While the appearance of unexpected IPs is often innocuous, especially for brands not typically targeted by phishing, it warrants investigation. Confirm that any observed IPs are authorized sending sources for your domain and not indicative of domain spoofing.
Marketer view
Marketer from Email Geeks explains that seeing an unexpected IP on SenderScore.org associated with a dedicated IP is a common occurrence, possibly related to email forwards.
3 May 2022 - Email Geeks
Marketer view
Marketer from Email Geeks responds that an unexpected IP on SenderScore is usually nothing to worry about and suggests checking DMARC reports for additional assurance against domain spoofing.
29 Jan 2025 - Email Geeks
What the experts say
2 expert opinions
The appearance of unacknowledged IP addresses on a SenderScore report for supposedly dedicated sending IPs often signifies that mail is indeed originating from those sources, or that a misconfiguration is linking them. Experts confirm that this occurrence is a direct reflection of actual email traffic attributed to the IP. A common explanation for such discrepancies is email forwarding, particularly when involving large Internet Service Providers, which can inadvertently reveal their IPs in reports. Ultimately, these unexpected entries suggest that a dedicated IP might not be as isolated as believed, or that other sending systems are operating without full awareness.
Key opinions
- Mail Flow Reflection: SenderScore's data, including unexpected IP addresses, directly reflects actual mail flow originating from or attributed to the IP. If an IP appears, it means mail is genuinely being sent from that source.
- Email Forwarding: A frequent cause of unexpected IPs on SenderScore is email forwarding, especially when emails pass through major ISPs like Cox. This can lead to the forwarding server's IP appearing in reputation reports.
- Configuration Issues: The presence of unexpected IPs can indicate underlying configuration problems, such as incorrect rDNS settings, that mistakenly link other IP addresses to your sending reputation.
- Additional Sending Systems: The appearance of these IPs suggests that mail might be sent from additional, perhaps unknown or overlooked, systems. This means your email environment is broader than initially perceived.
- Dedicated IP Misconception: If unexpected IPs show up, it implies that your supposedly dedicated IP might not be as isolated or exclusively used for your mail flow as you believed.
Key considerations
- Verify Actual Mail Flow: If an unexpected IP appears on your SenderScore report, it's crucial to investigate if mail is indeed being sent from that source, as the report reflects actual activity, not just potential associations.
- Inspect DNS and rDNS: Thoroughly review your DNS records, particularly rDNS, for any misconfigurations that might mistakenly link other IP addresses or networks to your dedicated sending IP.
- Audit All Sending Systems: Conduct a comprehensive audit of all systems and services that send email on behalf of your domain, including third-party integrations and internal applications, to ensure all sending sources are known and authorized.
- Investigate Unknown IPs: For any unfamiliar IP addresses, utilize public domain lookup tools, like searching the domain in Google, to gather information about the server or network associated with that IP.
- Re-evaluate Dedicated IP Setup: Consider whether your dedicated IP setup is truly isolated. The presence of unexpected IPs indicates that your email sending environment might be more complex or interconnected than initially assumed.
Expert view
Expert from Email Geeks confirms that an unexpected IP is likely related to forwarding, especially if it belongs to a major ISP like Cox, suggesting that searching the domain in Google can often reveal server information.
19 Feb 2025 - Email Geeks
Expert view
Expert from Word to the Wise explains that an IP address's reputation, including data seen on SenderScore, is a direct reflection of the actual mail flow originating from or attributed to that IP. If 'unexpected' IP addresses appear on a SenderScore report for a supposedly dedicated IP, it indicates that mail is indeed being sent from those other IPs, or there is a configuration issue, such as rDNS, linking them. This suggests that the IP might not be as dedicated or isolated as perceived, or that additional sending systems are unknowingly in use.
22 Dec 2022 - Word to the Wise
What the documentation says
6 technical articles
When unexpected IP addresses surface on SenderScore reports for a dedicated sending IP, it points to the sophisticated ways in which email reputation systems operate and how network infrastructure routes traffic. This phenomenon frequently stems from SenderScore's evaluation of broader network segments, such as entire IP blocks or Autonomous Systems (AS), rather than solely individual IPs. Consequently, activity from closely associated IPs within the same network or subnet can be aggregated. Furthermore, ancillary email functions like bounce processing, unsubscribe management, and link tracking often route through different, potentially shared, IP addresses, which are then picked up by reputation systems. Large cloud environments can also contribute, as their dynamic routing and load balancing may intermittently direct traffic through various, related IP ranges. Additionally, an IP's history, especially if it was recently recycled, can cause lingering reputation data from previous owners to appear. Finally, internal mail flow misconfigurations or unintended routing rules can inadvertently cause emails to originate from IPs other than the primary dedicated one.
Key findings
- Broad Network Reputation Assessment: Reputation systems like SenderScore extend their evaluation beyond individual IP addresses to include the reputation of the entire network block or Autonomous System (AS) to which an IP belongs. This can cause activity from other IPs within that shared range to appear.
- Ancillary Service Routing: Email-related functions such as processing bounces, managing unsubscribes, and tracking clicks or opens often use separate, potentially shared, IP addresses or domains. Reputation systems will incorporate activity from these additional IPs into your sending profile.
- Cloud Infrastructure Dynamics: In large-scale cloud environments, even with a dedicated IP, the underlying network infrastructure may occasionally route email traffic or related queries through different parts of its expansive IP ranges, leading to reports of activity from closely related or shared subnet IPs.
- Impact of IP History: A dedicated IP that has been recently acquired or recycled may temporarily reflect historical reputation data or associations from its previous owner, which can include activity from other IPs formerly used by that sender.
- Internal Mail Routing Errors: Organizations managing their own mail flow or using multiple internal relays might experience unexpected IP appearances due to misconfigured SMTP binds, incorrect routing rules, or other internal network settings that cause mail to originate from an unintended IP.
Key considerations
- Understand Network-Level Reputation: Recognize that email reputation is often assessed at the broader network or Autonomous System level, not just per individual IP. This means any poor standing of other IPs within your subnet can influence your dedicated IP's score.
- Audit All Associated Services: Thoroughly review all services and domains linked to your email sending, including those for bounce handling, unsubscribe requests, and tracking. These can utilize different IPs that contribute to your overall SenderScore.
- Account for Cloud Infrastructure Nuances: If operating in a cloud environment, be aware that dynamic routing, load balancing, or network transitions can cause your traffic to appear from various, related IP addresses, requiring a deeper understanding of your cloud provider's network behavior.
- Consider Recycled IP Implications: If your dedicated IP was recently acquired, research its history. Be prepared for a period where its SenderScore may reflect lingering reputation or associations from its previous owner, and monitor it closely.
- Review Internal Mail Flow Configurations: Inspect your internal SMTP configurations, routing rules, and network bindings to ensure that all outgoing mail is consistently originating from your intended dedicated IP, preventing accidental routing through other unauthorized or unexpected sources.
Technical article
Documentation from Validity Help Center explains that SenderScore evaluates IP addresses not just in isolation but often as part of larger IP blocks or network ranges. Unexpected IPs can appear if they are related to your network infrastructure, or if SenderScore aggregates data from closely associated sending entities, even if a primary dedicated IP is in use.
16 Aug 2022 - Validity Help Center
Technical article
Documentation from SendGrid Documentation explains that while a dedicated IP handles primary email sending, other services like bounce processing, unsubscribe management, or click and open tracking can sometimes route through different, potentially shared, IPs or domains. Reputation systems like SenderScore might pick up activity from these associated IPs, causing them to appear unexpectedly.
5 Mar 2025 - SendGrid Documentation
What should I do if an unexpected IP address appears in Google Postmaster Tools?
Why are Mailgun logs showing emails from unexpected sources using my dedicated IP?
Why do some IPs on SenderScore have different data ranges?
Why is Senderscore reporting millions of emails being sent from my IP address when I can't account for them?
Why is Senderscore showing a subdomain I don't recognize?
Why were my dedicated IPs listed on Spamhaus CSS after sending internal test emails?
