Summary
The core of the issue revolves around Sailthru users, monitoring their email deliverability with SparkPost, observing that some of their emails appeared to be sent through shared IP addresses, despite their expectation of using only dedicated IPs. This perceived discrepancy led to concerns, particularly since these unexpected shared IPs were sometimes identified on blocklists like SpamCop. Such a situation raises questions about the accuracy of reporting tools and the underlying infrastructure of email service providers (ESPs).
Key findings
- Reporting anomaly: A VP of Product at SparkPost clarified that the observed shared IP traffic was a reporting issue within their platform, not actual email sending through shared IPs. Internal filtering IPs were being incorrectly reported instead of the external dedicated IPs.
- Dedicated IP usage: Despite the reporting error, checks confirmed that the emails were indeed being sent via the customer's dedicated IP addresses, as intended.
- Discrepancy in campaigns: The campaigns associated with the erroneously reported shared IPs were not ones sent by the user's company, further indicating a data misrepresentation rather than a misconfiguration of their email sending setup.
- Volume difference: The volume of emails allegedly sent via shared IPs was significantly lower compared to the dedicated IP traffic, which was another clue pointing towards a reporting anomaly.
Key considerations
- Verify with ESP: When encountering unexpected IP activity, the first step should always be to consult with your ESP. They can provide clarity on their system's behavior and potential reporting nuances. For example, understanding how ESPs impact deliverability on dedicated IPs is crucial.
- Reporting accuracy: Deliverability monitoring tools can sometimes display misleading data due to how they interpret various network hops or internal routing. It's important to differentiate between actual sending behavior and reporting quirks.
- IP warming: Some ESPs use shared IP pools during an IP warming phase for dedicated IPs, directing overflow or initial volume to shared pools. Inquire if this is part of your ESP's standard procedure.
- Understanding IP types: Knowing what a shared IP address is and its potential impact is key, even when primarily using dedicated IPs.
What email marketers say
Email marketers often face complex deliverability challenges, and unexpected IP reporting can be a significant concern. Their experiences highlight the importance of diligent monitoring and proactive communication with ESPs to clarify discrepancies and ensure email campaigns maintain optimal deliverability.
Key opinions
- Initial concern: Marketers are naturally alarmed when their dedicated IP emails appear to be routed through shared IPs, especially if those shared IPs are blacklisted or blocklisted.
- Data scrutiny: They often dive deep into the data provided by monitoring tools, looking for patterns like traffic volume differences or unfamiliar campaign data associated with the unexpected IPs.
- Trust in ESPs: Despite concerns, there's an underlying trust that ESPs (like Sailthru or SparkPost) should provide accurate information and reliable infrastructure for dedicated IP sending. Marketers rely on maintaining dedicated IP reputation.
- Impact on deliverability: The primary worry is that shared IP usage (even if just perceived) could negatively impact their sending reputation and lead to deliverability issues, such as emails landing in spam or being blocked.
Key considerations
- Proactive monitoring: Marketers should consistently monitor their email sending metrics and IP behavior through tools like SparkPost, as identifying anomalies quickly is crucial. For example, checking blocklist checker is a good practice.
- Understanding ESP infrastructure: It is beneficial for marketers to understand the technical nuances of their ESP's setup, including how dedicated IPs function and if shared IPs are used for specific scenarios like overflow or warming.
- Verification process: When questions arise about IP usage, marketers should be prepared to provide their ESP with specific examples or data points to help diagnose the issue efficiently.
- Impact of shared IPs: Marketers need to be aware of the limitations of shared IP pools on authentication and control, even if they primarily use dedicated IPs.
Marketer view
Email marketer from Email Geeks shared observations of their SparkPost monitoring showing emails sent via additional shared IPs despite having dedicated IPs, leading to concerns about blacklisting on SpamCop.
Marketer view
Email marketer from Email Geeks queried whether the volume on the seemingly random IPs was comparable to their dedicated IPs or if it was smaller traffic.
What the experts say
Email deliverability experts stress the complexity of email infrastructure and the various factors that can influence how sending IPs are reported. They often look beyond the surface data, considering aspects like IP warming, internal routing, and the specifics of monitoring tool functionality to diagnose issues accurately.
Key opinions
- Diagnostic approach: Experts suggest systematically ruling out possibilities, starting with asking about volume and whether an IP warm-up is in progress when unexpected shared IPs appear.
- Reporting vs. sending: A key distinction for experts is between what a monitoring platform reports and what is actually happening in terms of mail routing. Discrepancies often point to reporting bugs rather than sending misconfigurations.
- ESPs' internal IPs: Many ESPs use internal filtering or relay IPs that might be picked up by monitoring tools but are not the actual external sending IPs. This is a common cause of confusion.
- Communication is key: The most effective solution is direct communication with the ESP's product or engineering team to investigate and resolve such reporting inaccuracies.
Key considerations
- Investigate all sources: Experts advise leveraging all available data, including SparkPost's campaign visibility and troubleshooting IP reputation issues to build a comprehensive picture.
- IP warm-up strategies: Consider if the issue aligns with a new dedicated IP or a change in sending volume that might trigger automated shared IP overflow, as this can affect why emails land in spam.
- Blacklist dynamics: Even if it's a reporting error, blacklisting of any IP associated with your sending domain (even incorrectly) can impact deliverability. Understanding how email blacklists actually work is critical.
- Platform limitations: Recognize that monitoring tools, while powerful, are not infallible and can have their own unique quirks or limitations in how they present data. Always cross-reference.
Expert view
VP of Product at SparkPost from Email Geeks confirms a reporting issue within their platform where internal filtering IPs were being picked up instead of the external dedicated IPs.
Expert view
Expert from Email Geeks inquired if the user was performing an IP warm-up and if an automated process was directing overflow volume to a shared IP pool.
What the documentation says
Official documentation from ESPs often details their IP allocation policies, the distinction between shared and dedicated IPs, and how deliverability metrics are calculated and presented. Understanding these technical specifications is crucial for anyone managing email programs, as it helps interpret monitoring data correctly and troubleshoot issues more effectively.
Key findings
- IP allocation policies: ESPs typically outline scenarios for dedicated versus shared IP usage, including policies for overflow, transactional emails, or warming periods.
- Reporting metrics: Documentation often clarifies how various IPs (including internal relays) might appear in logs or reports and how to correctly identify the ultimate sending IP.
- Troubleshooting guides: Many ESPs provide guides on diagnosing deliverability issues, including unexpected IP appearances, often recommending contacting support with specific details.
- Network architecture: Some documentation details the internal network routing which can explain why an email might pass through multiple IPs before exiting the ESP's infrastructure on a dedicated IP.
Key considerations
- Consult technical guides: Review your ESP's (e.g., SparkPost or Sailthru) technical documentation regarding IP management and API reporting to understand expected behavior.
- API interpretation: Ensure your monitoring tools correctly interpret ESP API responses, especially concerning headers or meta-data that indicate sending IPs versus internal routing IPs.
- Service level agreements: Understand the terms of your dedicated IP agreement, including any conditions under which shared IPs might be used (e.g., exceeding dedicated IP limits).
- Stay updated: ESPs update their systems and documentation frequently. Regularly check for updates that might explain changes in reported IP behavior.
Technical article
SparkPost documentation states that their platform provides detailed analytics on email sending, including IP addresses used, but clarifies that internal network IPs may occasionally appear in logs before mail exits on the dedicated sending IP.
Technical article
Sailthru's technical overview explains that dedicated IPs are assigned to clients for unique reputation management, and any perceived shared IP usage is likely due to reporting aggregation or system diagnostics.
Related resources
2 resources
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