How do I warm up a new IP address for transactional emails?
Michael Ko
Co-founder & CEO, Suped
Published 20 Jun 2025
Updated 13 Oct 2025
5 min read
It is a common misconception that emails which are exclusively transactional, like password resets or account activations, sent from a brand new dedicated IP address and sending subdomain, do not need to go through a warm-up process. However, this is not entirely accurate.
Even with high-engagement transactional emails, a new IP address lacks a sending history and reputation. Internet Service Providers (ISPs) like Google and Microsoft are wary of unknown senders to prevent spam, making a strategic warm-up crucial for ensuring your critical emails reach the inbox.
Why IP warming matters for transactional emails
Sender reputation is paramount in email deliverability. A new IP has no established reputation, making it appear suspicious to ISPs. They need to see consistent, positive sending behavior before trusting your emails, regardless of their nature or how important they are to your users.
Without proper warming, your perfectly legitimate transactional emails could be flagged as spam, temporarily deferred, or even blocklisted (blacklisted) by mail servers. This can lead to critical delivery failures for essential communications like order confirmations, security alerts, or two-factor authentication codes.
Warming is a proactive step to build trust and ensure that these time-sensitive communications reach your users reliably. For more general advice on building sender trust, explore this guide on how to warm up new IP addresses for email sending.
Crafting your IP warming strategy
The core principle of IP warming is a gradual increase in sending volume. Begin with a small, manageable volume to your most engaged users. This helps establish a positive sending pattern from the outset, signaling to ISPs that you are a legitimate sender.
Transactional emails are ideal for warming because they typically boast high open and click-through rates, indicating strong user engagement. Focus on emails with confirmed user interaction, such as password resets, account activations, or double opt-in confirmations, as these build positive reputation quickly.
If your transactional email volume is naturally high, consider a phased rollout. You can direct a portion of your transactional traffic to the new IP while gradually increasing the percentage over time, potentially using a round robin approach with existing IPs if you have them. This allows you to warm a dedicated IP without interrupting existing email campaigns.
Starting strong
Begin with 1,000-5,000 emails per day for the first few days. Some experts suggest you can comfortably start with up to 50,000 emails for pure transactional traffic, carefully monitoring performance. Consistency in sending is key, so avoid wild fluctuations in volume.
Maintain consistent sending frequency and volume as much as possible. Erratic sending patterns can raise suspicion with ISPs. As your positive reputation grows, you can gradually increase daily send limits. For more information on this, refer to what are the best practices for warming up new IPs for transactional emails.
Key technical considerations
Before sending any emails, ensure all your DNS records for email authentication, specifically SPF, DKIM, and DMARC, are correctly configured. These records verify your identity as a legitimate sender and are fundamental for deliverability. You can use a free DMARC record generator tool or review a simple guide to DMARC, SPF, and DKIM.
Closely monitor your bounce rates and spam complaint rates. High rates in the early stages can quickly damage your new IP's reputation, potentially leading to blocklisting (or blacklisting). If issues arise, a blocklist monitoring tool can help you identify and address them swiftly, preventing further damage.
Common pitfalls
Burst sending: Sending excessively large volumes of emails immediately upon launch.
Poor list hygiene: Sending to unengaged or invalid email addresses from the start.
Ignoring feedback loops: Failing to address spam complaints and other negative feedback.
Inconsistent volume: Drastically fluctuating daily send amounts, which appears suspicious to ISPs.
Effective strategies
Gradual ramp-up: Slowly increasing email volume over an extended period.
Engaged audience: Targeting your most active users for initial sends to build trust.
Monitor metrics: Keeping a close eye on bounces, complaints, and engagement rates.
Dedicated IP segregation: Using separate IPs for transactional versus marketing emails for clarity.
Leverage DMARC monitoring reports to gain visibility into your email authentication performance and identify any delivery issues. These reports provide invaluable insights into how ISPs are handling your mail, allowing you to react quickly to potential problems.
What to expect during warmup
In the initial phases, it is not uncommon to experience temporary deferrals. These are often ISPs testing the waters with your new IP address. Consistent positive engagement will help overcome these. If you encounter issues with a specific provider, like Yahoo, understanding how to resolve temporary deferral errors can be incredibly useful.
The duration of the warm-up period varies, typically ranging from a few weeks to a month or more, depending on your volume and sending behavior. Automated IP warm-up features from your email service provider can help, as mentioned by SendGrid's automated IP warm-up documentation. For an in-depth look, see how long it takes to warm up an IP address.
Day Range
Daily Volume
Notes
Day 1-3
1,000-5,000
Start with highly engaged transactional emails.
Day 4-7
5,000-10,000
Monitor engagement and deliverability closely.
Day 8-14
10,000-25,000
Gradually introduce more types of transactional emails.
Day 15-30
25,000-50,000+
Increase steadily based on positive feedback.
The ultimate goal is to achieve consistent deliverability without hitting any blocklists (blacklists) or experiencing significant deferrals. This ensures your transactional emails, which are critical for user experience, always land in the inbox.
Views from the trenches
Best practices
Start warming with your most highly engaged, real transactional emails, like password resets or OTPs.
Monitor performance metrics closely, especially bounce and complaint rates, during the initial sending days.
Consider a phased rollout for high-volume transactional senders, gradually moving traffic to the new IP.
Common pitfalls
Assuming transactional emails don't need warming due to their nature, leading to immediate high volume sends.
Ignoring temporary deferrals or early signs of deliverability issues, which can escalate into blocklisting.
Failing to have backup sending options or additional IPs for volume elasticity during the warm-up.
Expert tips
For transactional emails, starting with 50,000 daily volume on a new dedicated IP can be manageable if meticulously planned.
A well-managed setup with extra IP addresses can provide flexibility for volume bursts in the early stages of a large transactional sender launch.
Consistently monitoring email authentication reports, particularly DMARC, offers valuable insights into ISP treatment of your mail.
Expert view
Expert from Email Geeks says even transactional emails require warming, and sometimes you get lucky if daily volume is low enough to warm itself.
2023-11-07 - Email Geeks
Marketer view
Marketer from Email Geeks says gradual warm-up can be achieved by enabling triggered campaigns one by one, or in batches, depending on the volume they send.
2023-11-07 - Email Geeks
Ensuring long-term deliverability
Warming up a new IP address for transactional emails is not just a best practice, it is a critical investment in your email deliverability and sender reputation. It ensures that your most important messages consistently reach your users, fostering trust and reliability.
By following a methodical approach, focusing on engagement, and utilizing robust monitoring tools like Suped, you can build a strong reputation that will serve your email program well for the long term. This foundation will help you avoid deliverability issues and keep your email communication flowing smoothly.
Even with high-engagement transactional emails, a new IP address lacks a sending history and reputation. Internet Service Providers (ISPs) like 
Google and Microsoft are wary of unknown senders to prevent spam, making a strategic warm-up crucial for ensuring your critical emails reach the inbox.
Yahoo, understanding how to resolve temporary deferral errors can be incredibly useful.
Suped, you can build a strong reputation that will serve your email program well for the long term. This foundation will help you avoid deliverability issues and keep your email communication flowing smoothly.
