Summary
While major US email providers primarily rely on sender IP and domain reputation, sending behavior, and authentication to determine deliverability and throttling, anecdotal evidence suggests that IP geolocation can sometimes play a role. Most official documentation from providers like Gmail, Outlook.com, and Yahoo Postmaster Tools, along with insights from leading email marketing experts, emphasize that throttling decisions are predominantly driven by factors such as sender reputation, volume, complaint rates, and adherence to best practices, not the geographic location of the sending IP. However, specific instances have been reported where a US ISP throttled connections from non-USA geo-located IP addresses, and experts note that an IP's location can indirectly affect its perceived reputation, especially if it is in a region with a history of spam.
Key findings
- Reputation Dominates: For most major US email providers, deliverability and throttling are primarily determined by sender IP and domain reputation, built on consistent sending behavior, low complaint rates, and adherence to policies.
- Anecdotal Geo-Throttling: At least one major US ISP, Cox, has been reported to throttle email based on non-USA IP geolocation, citing 'too many concurrent connections' from international IPs.
- Indirect Reputation Impact: While not a direct throttling mechanism, the geographic location of a sending IP can influence its perceived reputation, particularly if it is associated with a region known for high spam volumes, potentially leading to deliverability challenges.
- Less Common in US: Unlike regions such as APAC, where geo-restriction policies are more prevalent, direct and explicit geo-based throttling by major US email providers is not a standard, widespread policy.
Key considerations
- Prioritize Reputation: Focus on building and maintaining a strong sender reputation through consistent volume, low bounce and complaint rates, and high subscriber engagement. This is the most crucial factor for deliverability.
- Ensure Authentication: Implement and maintain proper email authentication protocols, including SPF, DKIM, and DMARC, as these are critical for establishing sender trust regardless of IP location.
- Monitor Technical Errors: Pay close attention to transient errors like 'too many concurrent connections,' as these could indicate potential throttling, which might, in rare cases, be linked to IP geolocation for specific ISPs.
- Optimize for US Recipients: While not always required, considering US-based IPs for high-volume sending to US recipients could mitigate potential, albeit rare, geo-related throttling by certain domestic ISPs.
What email marketers say
9 marketer opinions
While the overwhelming majority of US email providers prioritize sender reputation, technical authentication, and user engagement as the primary determinants for email deliverability and potential throttling, the question of IP geolocation occasionally arises. Leading email marketing platforms and experts consistently emphasize that decisions to throttle emails are rooted in an IP's sending history and behavior globally, not merely its physical location. However, specific, albeit rare, instances have been reported, such as one encounter with a Cox representative, where non-USA geo-located IP addresses faced throttling due to issues like 'too many concurrent connections.' This suggests that while not a standard, explicit policy across the board, certain individual US ISPs might consider IP origin as one factor in their complex anti-abuse algorithms, alongside general traffic patterns from different regions. Ultimately, a robust sender reputation and adherence to best practices remain paramount.
Key opinions
- Primary Factor is Reputation: US email providers overwhelmingly rely on sender IP and domain reputation, built through consistent sending behavior, low complaint rates, and strong engagement, as the primary determinant for deliverability and throttling.
- Geo-Throttling Not Standard: Direct, explicit throttling by major US email providers based solely on a sender's IP geolocation is generally not a common or standard policy across the industry.
- Isolated Geo-Throttling Reports: Despite the general rule, there are documented, albeit isolated, cases where specific US ISPs, such as Cox, have throttled email from non-USA IP addresses due to perceived 'too many concurrent connections.'
- Regional Scrutiny Possible: IPs originating from regions historically associated with higher spam volumes may face increased scrutiny, which could lead to stricter filtering or implicit rate limiting, even without explicit geo-based throttling policies.
- ISP-Specific Considerations: Some email providers may incorporate IP location into their internal policy rules for setting appropriate sending limits, especially when managing diverse global email traffic or for their hosted customers.
Key considerations
- Focus on Core Deliverability Factors: Emphasize that building a strong sending reputation through consistent volume, low complaint rates, and high subscriber engagement remains the most crucial aspect for deliverability, regardless of IP location.
- Verify Email Authentication: Ensure all emails are properly authenticated with SPF, DKIM, and DMARC, as these are fundamental trust signals that are prioritized over most geographical concerns by US email providers.
- Analyze Error Messages Carefully: Pay close attention to specific error messages, especially those indicating 'too many concurrent connections,' as these could, in isolated cases, point to ISP-specific geo-based rate limiting or throttling.
- Evaluate IP Geography for Targeted Markets: For senders with significant traffic to a specific country like the US, using an IP located within that region can sometimes help align with an ISP's typical traffic patterns, potentially reducing rare geo-related scrutiny.
- Stay Informed on ISP Policies: Regularly consult postmaster pages and industry forums for major US email providers to stay updated on any evolving deliverability policies or reported throttling behaviors, however rare they may be.
Marketer view
Marketer from Email Geeks shares a conversation with a Cox representative, who stated that 'too many concurrent connections' errors can occur when sending from non-USA geo-located IP addresses (e.g., Austria) and that they throttle based on this. The representative advised sending from USA-based IPs when targeting USA providers, noting a drastic drop in transient errors after changing IP geolocation.
18 Oct 2023 - Email Geeks
Marketer view
Marketer from Email Geeks explains that email providers generally see more email traffic from their own country and surrounding regions, allowing sending limits to be adjusted accordingly alongside other factors. He adds that hosted customers may have a variety of policy rules, which can include checks on IP location to help set suitable sending limits across different time windows.
11 Sep 2021 - Email Geeks
What the experts say
2 expert opinions
While direct throttling by US email providers based solely on sender IP geolocation is not a standard practice, unlike some regions such as APAC, the geographic location of an IP can subtly influence its perceived reputation and, consequently, email delivery. Experts indicate that US providers predominantly rely on an IP's overall sending reputation, built on consistent behavior, rather than its physical location. However, an IP located in a region with a poor sending history might face increased scrutiny, potentially leading to deliverability challenges, including implicit throttling or blocking, as its reputation could be negatively affected by the regional association.
Key opinions
- Geo-Throttling Less Common in US: Direct throttling by US email providers based solely on a sender's IP geolocation is not a widespread or common policy, unlike in some other regions such as APAC, particularly China.
- Indirect Reputation Influence: An IP's geographic location can indirectly affect its perceived reputation, influencing filtering and delivery decisions by US providers. If an IP is in a region with a poor sending reputation, it might inherit negative associations.
- Reputation Outweighs Location: For US email providers, sender IP and domain reputation, built on sending behavior, authentication, and engagement, are the primary drivers of deliverability and throttling decisions, rather than the physical location of the IP.
- Speculation, Not Policy: The idea of a US provider explicitly limiting mail from, for example, the EU based on geolocation is considered 'interesting' but not a standard, published policy, suggesting it's rare or theoretical.
Key considerations
- Prioritize Overall Reputation: Focus on building a strong sender reputation through consistent volume, low complaint rates, and high subscriber engagement. This remains the most significant factor for email deliverability, overshadowing geographic considerations.
- Assess IP Region Reputation: Be aware that an IP's geographic location can, at times, indirectly influence its perceived reputation, especially if the region is known for a high incidence of spam. Consider this when choosing server locations or ESPs.
- Monitor for Unexpected Delays: While uncommon, if you experience unexplained throttling or blocking when sending to US providers from international IPs, investigate if regional reputation or very specific, rare ISP policies could be contributing factors.
- Consider Global Traffic Patterns: When sending large volumes globally, understand that different regions may have varying policies or perceived risk factors associated with IP geolocation, even if US providers generally do not directly throttle by geo.
Expert view
Expert from Email Geeks shares his experience, stating that he has primarily encountered geo-restriction policies in APAC, specifically China. He finds it an 'interesting thought' that a US provider would limit mail from the EU, implying it is less common but not impossible.
1 Jul 2022 - Email Geeks
Expert view
Expert from Word to the Wise explains that IP geolocation can influence email delivery and filtering decisions. While not directly stating US providers throttle solely based on location, she notes that an IP's geographic location can affect its perceived reputation. For example, a US sender using a server in a region with a poor sending reputation might experience deliverability issues, including throttling or blocking, because the IP inherits the regional reputation.
5 Apr 2023 - Word to the Wise
What the documentation says
5 technical articles
Official documentation from leading US email providers and major email service platforms consistently indicates that email throttling is based on sender IP and domain reputation, sending behavior, and adherence to best practices, rather than the geographic location of the sending IP. Providers like Gmail, Outlook.com, and Yahoo, along with platforms such as SendGrid and AWS SES, detail that factors like consistent sending volume, low bounce and complaint rates, and robust authentication protocols (SPF, DKIM, DMARC) are the primary determinants of deliverability and any potential throttling decisions.
Key findings
- Reputation-Driven Throttling: Major US email providers like Google, Microsoft, and Verizon Media, along with platforms like SendGrid and AWS SES, base their throttling decisions overwhelmingly on sender IP and domain reputation, not IP geolocation.
- Geolocation Not a Factor: Official postmaster documentation consistently omits sender IP geolocation as a direct factor influencing email throttling or deliverability limitations.
- Behavioral Metrics are Key: Deliverability and throttling are determined by critical sending metrics, including consistent volume, low bounce rates, minimal spam complaints, and adherence to policy guidelines.
- Authentication is Crucial: The proper implementation of email authentication protocols, such as SPF, DKIM, and DMARC, is highlighted as essential for establishing sender trust and avoiding throttling.
Key considerations
- Focus on Reputation: To ensure optimal deliverability to US recipients, prioritize building and maintaining a strong sender reputation through consistent, high-quality sending practices and list hygiene.
- Adhere to Best Practices: Consistently follow recommended email sending best practices, including managing subscriber engagement and adhering to anti-spam policies, as outlined by major providers.
- Monitor Performance Data: Regularly monitor email performance metrics, such as bounce rates, complaint rates, and engagement, using available postmaster tools to proactively address any issues affecting deliverability.
- Implement Authentication: Ensure all outgoing emails are properly authenticated with SPF, DKIM, and DMARC records, as these foundational elements are critical for establishing credibility with US email providers.
Technical article
Documentation from Google Postmaster Tools Help explains that Gmail's deliverability is primarily influenced by the sender's IP and domain reputation, which is built on sending behavior, history, and adherence to best practices, rather than the geographic location of the sending IP. Throttling is related to these reputation metrics and abuse patterns.
26 Apr 2022 - Google Postmaster Tools Help
Technical article
Documentation from Outlook.com Postmaster explains that Microsoft's systems evaluate sending IPs based on their reputation, volume, spam complaint rates, and adherence to their policies. There is no explicit mention of throttling based on the geographic location of the sender's IP address, suggesting deliverability is linked to sending behavior and trust.
15 Sep 2023 - Outlook.com Postmaster
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