Summary
Gmail throttling during IP warming and delayed IP reputation updates are multifaceted issues. Several factors contribute, including: exceeding Gmail's complex sending limits (especially with new IPs), poor IP/sender reputation stemming from low engagement, spam complaints, sending to unengaged users (dirty lists), authentication problems (SPF, DKIM, DMARC), and content triggering spam filters. Gradually increasing sending volume, maintaining list hygiene, monitoring engagement, and adhering to email best practices are crucial for building a positive reputation and preventing throttling. Senders often overestimate engagement and should ensure robust engagement filters and implement segmented sending strategies.
Key findings
- Gmail's Algorithm: Gmail utilizes a complex algorithm to determine sending limits, particularly stringent for new IPs undergoing warming.
- Poor Sender Reputation: Low engagement, spam complaints, and sending to unengaged recipients collectively contribute to poor sender reputation, triggering throttling.
- Authentication Failures: Incorrect or missing SPF, DKIM, and DMARC records lead to authentication failures, causing deliverability problems and throttling.
- Content Issues: Spammy keywords, poor formatting, or content triggering spam filters result in throttling and reduced inbox placement.
- List Hygiene: Sending to 'dirty' lists with unengaged or invalid addresses increases bounce rates and spam complaints, negatively impacting reputation.
- Engagement Overestimation: Senders often overestimate actual engagement, leading to ineffective sending strategies and potential negative impact.
Key considerations
- Gradual Volume Increase: Implement a gradual, consistent increase in sending volume to establish a positive sending reputation over time.
- List Segmentation: Segment email lists based on engagement levels, prioritizing sending to highly engaged subscribers during the warming process.
- Authentication Setup: Ensure proper configuration and validation of SPF, DKIM, and DMARC records for effective email authentication.
- Content Optimization: Review email content for spam triggers, improve formatting, and test with spam checkers to enhance deliverability.
- List Cleaning Practices: Regularly clean email lists by removing inactive and unengaged subscribers to maintain list hygiene.
- Engagement Monitoring: Monitor engagement metrics (opens, clicks), bounce rates, and spam complaints to identify and address deliverability issues proactively.
- Sender Reputation Monitoring: Use tools like Google Postmaster Tools and Sender Score to continuously monitor IP and domain reputation.
What email marketers say
11 marketer opinions
Gmail throttling during IP warming can stem from multiple factors. Poor sender reputation, often due to low engagement, spam complaints, and sending to unengaged users, is a primary cause. Authentication issues (SPF, DKIM, DMARC) and content triggering spam filters also contribute. Overestimating engagement, failing to segment lists effectively, and neglecting email list hygiene exacerbate the problem. Furthermore, issues not directly related to sending such as offline guest data can contribute.
Key opinions
- Sender Reputation: Poor sender reputation, resulting from low engagement, spam complaints, and sending to unengaged recipients, directly leads to throttling.
- Authentication: Authentication errors (SPF, DKIM, DMARC) can cause Gmail to throttle emails, regardless of volume.
- Content Issues: Email content that triggers spam filters, contains spammy keywords, or lacks proper formatting can result in throttling.
- List Hygiene: Poor list hygiene, including sending to inactive or unengaged subscribers, negatively impacts deliverability and contributes to throttling.
- Engagement Overestimation: Overestimating email engagement metrics can result in sending to users who don't actually engage, increasing spam complaints.
Key considerations
- Monitor Reputation: Actively monitor sender reputation through tools like Google Postmaster Tools and Sender Score to identify and address issues promptly.
- Audit Authentication: Ensure proper setup and validation of SPF, DKIM, and DMARC records to authenticate your emails.
- Refine Content: Review email content for spammy keywords, phrases, and formatting issues, testing with different email clients and spam checkers.
- Clean Email Lists: Implement a consistent email list cleaning process to remove inactive and unengaged subscribers.
- Segment Lists: Segment email lists based on engagement levels, sending to highly engaged segments first and gradually increasing volume to new segments.
- Engagement Filters: Ensure your engagement filters are robust. Consider offline data and tailor content to be more personal and engaging.
Marketer view
Email marketer from Reddit suggests that Gmail throttling might be related to content triggering spam filters. They advise reviewing email content for spammy keywords or phrases, ensuring proper formatting, and testing with different email clients and spam checkers.
9 Jul 2021 - Reddit
Marketer view
Email marketer from Email Geeks explains that content issues could cause negative user reactions leading to spam reports. Suggests trying different content and increasing engagement filters, also asks if the IP address is used for anything else.
10 May 2023 - Email Geeks
What the experts say
2 expert opinions
Gmail throttling during IP warming, coupled with delayed IP reputation updates, is often attributed to inconsistent sending behavior and sending to 'dirty' lists. Building a positive IP reputation necessitates time, consistent effort, and a steady volume increase. Sending to unengaged or invalid addresses triggers high bounce rates and spam complaints, severely impacting sender reputation.
Key opinions
- IP Reputation Building: Building a positive IP reputation requires time, consistent effort, and a steady, gradual increase in sending volume.
- Inconsistent Sending: Erratic or inconsistent sending behavior during IP warming can trigger Gmail throttling.
- Dirty Lists: Sending to 'dirty' lists containing unengaged or invalid addresses leads to high bounce rates and spam complaints.
- Negative Impact: High bounce rates and spam complaints from sending to 'dirty' lists negatively impact sender reputation, causing Gmail to throttle sending volumes.
Key considerations
- Consistency: Maintain a consistent and steady increase in sending volume during IP warming to avoid erratic behavior.
- List Hygiene: Prioritize list hygiene by removing unengaged or invalid addresses to minimize bounce rates and spam complaints.
- Gradual Increase: Implement a gradual increase in email volume, instead of sudden spikes, to establish a positive reputation.
- Engagement Focus: Focus on sending to engaged users to build and maintain a positive sending reputation.
Expert view
Expert from SpamResource explains that building a positive IP reputation takes time and consistent effort. Gmail may throttle emails from newly warmed IPs if the sending behavior is erratic or inconsistent. Ensure a steady increase in volume and maintain high engagement rates to improve IP reputation.
29 Oct 2021 - SpamResource
Expert view
Expert Laura Atkins from Word to the Wise responds that a common reason for throttling during IP warming is sending to a 'dirty' list. Even with good engagement from a subset of users, sending to unengaged or invalid addresses will lead to high bounce rates and spam complaints, negatively impacting sender reputation and causing Gmail to throttle sending volumes.
20 Aug 2022 - Word to the Wise
What the documentation says
5 technical articles
Gmail throttling during IP warming and delayed IP reputation updates are often due to exceeding sending limits set by complex algorithms, especially with new IPs. Poor IP reputation directly affects deliverability, leading to throttling or blocking. Gradual volume increases are crucial for establishing a positive sender reputation, along with monitoring engagement metrics, bounce rates, and spam complaints. Email content and structure also play a vital role; adhering to email best practices is essential.
Key findings
- Sending Limits: Gmail uses complex algorithms to determine sending limits, and exceeding these during IP warming leads to throttling.
- IP Reputation Impact: Poor IP reputation directly affects deliverability, resulting in throttling or blocking by ISPs.
- Gradual Volume Increase: Warming an IP address requires gradually increasing sending volume over time to build a positive reputation.
- Content and Structure: Email content and structure significantly impact deliverability; non-compliant content can lead to throttling.
- Quotas: Exceeding sending quotas can trigger throttling, necessitating a gradual increase within allowed limits.
Key considerations
- Monitor IP Reputation: Use tools like Google Postmaster Tools and Sender Score to monitor IP reputation and address issues promptly.
- Monitor Engagement: Monitor engagement metrics, bounce rates, and spam complaints to identify deliverability issues.
- Adhere to Best Practices: Ensure emails follow best practices, including unsubscribe links, contact information, and proper email structure.
- Stay Within Quotas: Gradually increase sending volume within the allowed quotas to establish a good sender reputation.
- Address Deliverability: If throttling occurs, reduce volume and address identified deliverability issues.
Technical article
Documentation from Microsoft explains that email content can affect email deliverability. Ensure that the emails follow email best practices such as including unsubscribe links, contact information, and proper email structure. Poorly structured emails are often throttled.
31 Mar 2025 - Microsoft
Technical article
Documentation from SparkPost explains that warming an IP address involves gradually increasing sending volume over time to establish a positive sending reputation. They recommend starting with small volumes and monitoring engagement metrics closely. Throttling indicates a need to reduce volume or address deliverability issues.
17 Dec 2024 - SparkPost
