What is the best approach for warming up a new IP address for a newsletter with high volume sends?
Michael Ko
Co-founder & CEO, Suped
Published 21 Jun 2025
Updated 18 Aug 2025
6 min read
Warming up a new IP address for high-volume newsletter sends can feel like walking a tightrope. On one side, you have the urgency of reaching your audience, and on the other, the risk of hitting spam filters and tanking your sender reputation. The goal is to gradually introduce your new IP to internet service providers (ISPs) like Google and Microsoft, building trust and a positive sending history over time.
For a weekly newsletter that reaches a million subscribers, alongside daily transactional and marketing emails, the traditional warming schedules might seem too slow. The challenge intensifies when a significant portion of your newsletter audience has meh engagement. This requires a strategic, engagement-focused approach to your IP warm-up to prevent deliverability issues from the start.
Core principles of IP warming
The fundamental principle of IP warming is to start with low volumes of highly engaged recipients and gradually increase your send volume and expand your audience segments. This teaches ISPs that your email traffic is legitimate and desired, building a positive sender reputation for your new IP address. This careful ramp-up helps avoid triggering spam traps or getting blocklisted (or blacklisted).
Consistency is key. ISPs prefer a steady, predictable sending pattern. Sudden spikes in volume, even after some warming, can raise red flags. This means that if your newsletter creates a massive weekly peak, you'll need a strategy to smooth out that volume during the warming period.
Engaged users are your best friends during this period. The more opens, clicks, and replies you get, the stronger your reputation becomes. This is why prioritizing your most active segments in the early stages of warming is crucial. For more details on the importance of engagement, you can refer to Twilio SendGrid's guide to IP warm up.
Focus on high engagement for warming
During IP warming, the content you send and the audience you send it to are paramount. Prioritize highly engaging content sent to your most active subscribers. This ensures positive feedback from ISPs, accelerating your reputation building. Avoid sending to unengaged segments until your IP is fully warmed.
Building your high-volume schedule
Given your scenario of a weekly newsletter and daily sends, a straightforward daily volume increase might not suffice. A stair-stepping approach, where you maintain a specific volume for a few days before increasing again, is generally not considered bad practice. In fact, it can be a smart way to manage the inherent peak of a weekly newsletter while allowing ISPs to adjust to your new sending patterns.
Instead of pushing the entire one-million-subscriber newsletter at once during a specific weekly send, you could break it down. For example, distribute the newsletter content over two or three days during the warm-up phase, sending to smaller, highly engaged segments each day. This maintains a more consistent daily volume and helps avoid the sudden, large spikes that ISPs dislike.
Your daily transactional and marketing emails can run concurrently, but their volumes should also scale gradually. Integrate them into the overall warming plan, ensuring their send volumes also increase incrementally. The key is to manage the total daily volume across all email streams.
A typical warming schedule spans 15 to 60 days, depending on your total volume and desired velocity. For high-volume senders, a longer warm-up period, possibly 45-60 days, is often recommended to establish a robust reputation. You can find more comprehensive examples in resources like Rejoiner's guide on IP warming, or for more general guidance on schedules, refer to our page on IP warming best practices and schedules.
Week
Daily Volume (approx.)
Audience Type
1
10,000 - 50,000
Most engaged (opened/clicked in last 30 days)
2
50,000 - 150,000
Engaged (opened/clicked in last 60 days)
3
150,000 - 300,000
Recently active (opened/clicked in last 90-120 days)
4+
300,000+ to target peak
All active subscribers, gradually including less engaged
Leveraging technical capabilities
Many email service providers (ESPs) and sending platforms offer built-in IP warming features. These often allow you to set specific daily send limits and will automatically distribute your sends across the new and potentially old IPs, ensuring a smooth transition. This can greatly simplify the process, especially for large volumes.
If your ESP doesn't have an automated warm-up feature, you might need to manage sending rates at the Message Transfer Agent (MTA) level. This involves configuring your MTA to throttle sends at a certain rate, distributing the volume over a longer period each day. This ensures a consistent flow of mail, even if your campaigns are set to send immediately.
Another powerful strategy is to gradually shift traffic. For example, if you have an existing warmed IP, you can start by sending a small percentage of your newsletter (e.g., 5%) from the new IP, slowly increasing that percentage over time. This ensures no interruption to existing campaigns while the new IP builds its reputation.
Manual IP warming
Control: Requires meticulous daily tracking of volumes and delivery rates.
Flexibility: Adapt volume increases based on real-time feedback and ISP responses.
Complexity: Can be time-consuming and prone to human error, especially for high volumes.
Automated IP warming (via ESP)
Efficiency: ESPs automatically manage the volume ramp-up across IPs.
Seamless: Often provides uninterrupted service by blending new and old IP traffic.
Monitoring: ESPs typically provide tools to track warm-up progress and deliverability.
Monitoring and maintaining reputation
Careful monitoring during the warm-up period is non-negotiable. Watch your deliverability metrics closely. Look for spikes in bounce rates (especially hard bounces), complaints, or deferrals. These are early warning signs that you might be increasing volume too quickly or sending to unengaged segments.
Pay particular attention to feedback loops from major ISPs. If you start seeing an increase in spam complaints, it's a clear signal to pull back on volume or re-evaluate your audience segmentation. Remember, the goal is not just to send emails, but to get them into the inbox and ensure positive recipient engagement. For more insights on improving deliverability, review technical solutions for top performing senders.
Maintaining a clean list and proper email authentication (like SPF, DKIM, and DMARC) is critical both during and after the warming period. These practices signal to ISPs that you are a legitimate sender and help protect your sender reputation long-term.
Common pitfalls to avoid
Sending too much too soon: Large, sudden volumes can lead to immediate spam folder placement.
Ignoring engagement: Sending to disengaged subscribers during warm-up harms reputation.
Inconsistent volume: Erratic sending patterns make it difficult for ISPs to trust your IP.
Lack of monitoring: Not watching metrics can cause problems to escalate quickly.
Views from the trenches
Best practices
Start with your most engaged subscribers to build initial positive sending reputation.
Gradually increase daily send volume and expand to less engaged segments over weeks.
Use MTA-level throttling or ESP-provided automated warming features for consistency.
Distribute large newsletter sends over multiple days to avoid volume spikes.
Common pitfalls
Sending the full newsletter volume immediately from a new IP.
Prioritizing quantity over quality and engagement during warm-up.
Ignoring feedback loops and complaint rates from ISPs.
Failing to implement proper email authentication (SPF, DKIM, DMARC).
Expert tips
Consider a phased rollout where a percentage of sends go through the new IP and the rest through the old one.
Leverage every available sending day to maximize velocity during the warm-up period.
For complex high-volume scenarios, a simpler, automated throttling approach can be less error-prone.
If possible, use your ESP's dedicated IP warming features as they often handle the intricate logic automatically.
Expert view
Expert from Email Geeks says setting a throttle at the MTA level and segmenting the audience by recent engagement is ideal for warm-up.
December 20, 2024 - Email Geeks
Marketer view
Marketer from Email Geeks says they automated a monthly newsletter to distribute slowly over the entire month to manage its large volume.
December 20, 2024 - Email Geeks
Summary of best practices
Warming up a new IP for high-volume newsletter sends requires a strategic blend of gradual volume increases, audience segmentation, and diligent monitoring. Embrace the stair-stepping method for your weekly newsletter to smooth out volume peaks, prioritize your most engaged subscribers, and leverage automated tools or MTA throttling for consistency. By following these practices, you can successfully build a strong sender reputation and ensure your emails reliably reach the inbox.
Google and 
Microsoft, building trust and a positive sending history over time.
