Summary
The optimal IP warming strategy, whether ISP-based or volume-based, depends on a multitude of factors. An ISP-based approach provides granular control and can yield excellent results, but it requires more micromanagement. Volume-based warming is generally easier, especially with the improvements in provider reputation tracking. It involves maintaining consistent sending habits, closely monitoring engagement metrics, bounce rates, spam complaints, and sender reputation. Key practices include segmenting recipient lists by engagement level and ISP, prioritizing the most engaged users, adapting strategies to comply with requirements from major ISPs such as Gmail and Microsoft, ensuring the content is high-quality and non-promotional, and maintaining a clean, validated email list. The decision between ISP-based and volume-based often depends on the email list size and quality, and the existing deliverability issues, while avoiding sudden spikes in volume during the warming process is crucial.
Key findings
- Strategy Choice: The choice between ISP-based and volume-based warming depends on list size, quality, existing deliverability issues, and operational resources.
- ISP Requirements: Tailoring IP warming strategy to comply with major ISPs is essential, which includes monitoring Gmail spam rates using Postmaster Tools.
- List Hygiene: Email list quality impacts the IP warming strategy. In particular maintaining low bounce rates and spam complaints.
- Gradual increase: Gradual increase volume is important. In particular avoiding sudden spikes.
- Break out Microsoft: The email marketers found it useful to “break out microsoft” in this case meaning focusing on Microsoft specific deliverability.
- Quality content: It is important to start the process with high quality and valued email content
Key considerations
- Granularity vs. Overhead: Assess the workload required to segment and monitor each ISP separately vs. managing overall volume.
- Engagement Focus: Prioritize sending to the most engaged users first to build a positive reputation.
- Proactive Communication: Consider contacting the support teams of major ISPs like Microsoft for guidance.
- Feedback Loop Analysis: Monitor sending reputation, bounce rates, complaint rates, and feedback loops to ensure compliance and maintain quality.
- Reverse DNS Setup: Ensure that a reverse DNS (rDNS) record is correctly configured for your sending IP address.
- Strategic approach: Implement a strategic approach to follow key metrics for better deliverability. Metrics such as open rates.
- Time Commitment: A typical IP warming strategy timeline might take up to 4-8 weeks
What email marketers say
18 marketer opinions
The best IP warming strategy, whether ISP-based or volume-based, depends on various factors, including list size, list quality, sending history, deliverability issues, and the level of micromanagement a sender can handle. A granular, ISP-based approach can yield excellent results, while volume-based warming is often easier and effective, especially with improvements in provider reputation tracking. It is a common approach for those with diverse lists. Consistency in sending volume and schedule is crucial, along with close monitoring of engagement metrics, bounce rates, complaint rates, and sender reputation. Segmenting recipient lists by engagement level and ISP, prioritizing engaged users, and adapting to the specific requirements of ISPs like Gmail and Microsoft are also important considerations. High-quality, engaging content and a clean, validated email list are essential for a successful warm-up.
Key opinions
- Granularity vs. Ease: ISP-based warming offers more control but requires significant micromanagement; volume-based is simpler but relies on improved provider reputation tracking.
- Segmentation: Segmenting by engagement level and ISP is crucial for prioritizing engaged users and tailoring warming strategies.
- Consistency: Maintaining a consistent sending volume and schedule is essential for building trust with ISPs.
- Monitoring: Closely monitoring engagement metrics, bounce rates, complaint rates, and sender reputation is necessary to identify and address any issues during warming.
- Content Quality: High-quality, engaging content is essential, especially during the initial warm-up phase, to encourage positive engagement.
- List Hygiene: Starting with a clean, validated email list is crucial to minimize bounces, complaints, and spam trap hits.
- Personalization: Tailoring warming strategies to specific ISPs, like Gmail and Microsoft, is recommended due to their unique requirements and monitoring tools.
- Gradual Increase: Gradually ramp up the sending volume is important. The amount ramped up should increase from 50-100% each day, or every other day. Adjust based on performance and feedback loops.
Key considerations
- List Size: Smaller lists may be warmed effectively with a volume-based approach, while larger lists may benefit from a more granular ISP-based strategy.
- List Quality: The quality of your email list will impact the optimal warming strategy. It is important to send emails only to the “best” email addresses.
- Deliverability History: If you have a history of deliverability issues at specific ISPs, consider an ISP-based approach or increased caution during warming.
- Micromanagement Capacity: Assess your capacity for micromanagement when deciding between ISP-based and volume-based warming strategies.
- Timeframe: Understand that the ideal IP warming timeframe is from 4-8 weeks. You must monitor your deliverability to ensure accurate timescales are met.
- Breaking out Microsoft: Breaking out Microsoft during warming might have additional benefits and remove warming hiccups.
- Content Quality: Email content needs to be high quality and not promotional, this should be valuable and appreciated.
- Engagement metrics: Focus on engagement metrics such as, open rates, click through rates and unsubscribe rates during IP warming.
Marketer view
Email marketer from Validity Blog shares the importance of closely monitoring your sending reputation, bounce rates, complaint rates, and blocklist status during IP warming. They say to be prepared to adjust your sending strategy if you see negative indicators.
13 Mar 2024 - Validity Blog
Marketer view
Email marketer from Email Geeks has always done volume based but focused on the ISP. He sends to all ISPs, but the way he does this is he always looks at the ISP with the largest volume and start his volume minimums there. All of the other ISPs with a lesser volume just fall in behind that until you reach full volume required for the client, Gmail is almost always the largest, so he will start at 5000 emails per day per IP address based on the percentage of Gmail addresses in the list and then after three or four days increase volume 1.5×-2x every two days until full volume is reached while monitoring each individual ISP along the way and adjust as needed.
16 Jan 2025 - Email Geeks
What the experts say
3 expert opinions
Experts suggest that the choice between volume-based and ISP-based IP warming strategies depends on several factors. For ease of implementation, volume-based warming can mimic the effects of ISP-based warming through random segmentation, keeping per-ISP levels low. However, the optimal strategy often depends on list size and quality; smaller lists may be sufficiently warmed with a volume-based approach, while larger lists may require a more granular, ISP-focused method. Regardless of the chosen method, a slow and consistent increase in sending volume is crucial to avoid triggering spam filters.
Key opinions
- Volume-based Mimicry: Volume-based warming can effectively mimic ISP-based warming through random segmentation, reducing the workload.
- List Size Impact: Optimal strategy depends on list size with smaller lists suitable for volume-based and larger lists for ISP-based.
- Consistent Increase: Slow and consistent volume increase is crucial, preventing sudden spikes that trigger spam filters.
Key considerations
- Segmentation Effort: Evaluate the effort required for random segmentation when implementing volume-based warming.
- List Granularity: Consider the level of granularity needed for your specific list and whether a volume-based approach will suffice.
- Ramp-Up Pace: Carefully plan the ramp-up pace to ensure a gradual and consistent increase in sending volume over time.
- List Quality: Consider the quality of your list when deciding on what ramp up strategy to use.
Expert view
Expert from Word to the Wise explains the importance of slowly and consistently increasing sending volume during IP warming. Avoid sudden spikes in volume, which can trigger spam filters.
15 Sep 2021 - Word to the Wise
Expert view
Expert from Email Geeks shares his goal with volume based warming was always to just keep per-ISP levels low enough through random segmentation as to basically keep the effects the same as if you were doing it at a per-ISP level, so he always preferred volume-based because it’s less work and easier segmentation.
17 Sep 2021 - Email Geeks
What the documentation says
4 technical articles
Email deliverability documentation emphasizes starting with low sending volumes, especially on new IPs, and gradually increasing over weeks. Close monitoring of bounce rates, feedback loops, and sending reputation is critical. For Gmail, maintain a low spam rate. While there are no specific volume thresholds (Microsoft), consistent sending habits and low complaint rates are vital. Proper reverse DNS configuration is essential to verify IP legitimacy.
Key findings
- Low Initial Volume: Begin with very low sending volumes, especially on new IPs.
- Gradual Increase: Gradually increase volume over weeks, not days.
- Reputation Monitoring: Closely monitor sending reputation, bounce rates, and feedback loops.
- Gmail Spam Rate: For Gmail, maintain a consistently low spam rate (below 0.1%).
- Consistent Habits: Consistent sending habits are key to building a positive reputation with Microsoft.
- rDNS Configuration: A properly configured reverse DNS record is essential for IP legitimacy.
Key considerations
- New IP Sensitivity: Exercise extra caution when warming up a new IP address.
- ISP-Specific Guidelines: Pay attention to ISP-specific guidelines, such as Gmail's spam rate threshold.
- Complaint Rate: Strive to maintain low complaint rates as emphasized by Microsoft.
- Technical Setup: Ensure correct technical configuration, including reverse DNS records.
- Adaptability: Be prepared to adapt based on the above key findings for your particular situation.
Technical article
Documentation from Microsoft Sender Support emphasizes that there aren't specific volume thresholds for IP warming, but shares that consistent sending habits and low complaint rates are key to building a positive reputation. Monitor your sending reputation in the Smart Network Data Services (SNDS).
8 Apr 2024 - Microsoft Sender Support
Technical article
Documentation from RFC-1912 explains the importance of having a properly configured reverse DNS (rDNS) record for your sending IP address. This helps ISPs verify that your IP address is legitimate and not associated with spamming activity.
30 Aug 2023 - RFC-1912
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