How to maintain dedicated IP reputation with ISPs for email sending?
Michael Ko
Co-founder & CEO, Suped
Published 9 May 2025
Updated 15 Aug 2025
6 min read
When you choose to use a dedicated IP address for your email sending, you gain significant control over your sender reputation. Unlike shared IPs, where your deliverability can be impacted by the sending practices of others, a dedicated IP means your reputation is entirely your own to build and maintain. This control comes with responsibility, however, as you must actively manage its standing with Internet Service Providers (ISPs).
Maintaining a strong dedicated IP reputation is crucial for ensuring your emails consistently reach the inbox, avoiding spam folders and blocklists (or blacklists). It requires a strategic approach, consistent effort, and a keen understanding of how ISPs evaluate sending behavior. I'll share key strategies and practices to help you cultivate and preserve a positive reputation for your dedicated IPs.
Understanding IP reputation and its nuances
Understanding how ISPs perceive your email sending is the foundation of effective IP reputation management. It is not just about the volume of emails you send, but the quality and consistency of that volume. ISPs closely monitor various metrics to determine if your IP address is a trustworthy source of email.
While IP reputation was once the primary factor, today's email filters are more sophisticated, taking into account multiple reputation systems. These systems include not only IP reputation, but also domain reputation and other indicators. These factors often work in concert, meaning a good IP alone may not be enough if your domain has issues, or vice-versa. You might need to consider how your email service provider affects deliverability.
For a comprehensive approach to improving your sender reputation, it's important to monitor all aspects. ISPs will often provide feedback, for example through bounce codes or throttling, when you do not have sufficient reputation for the volume you are attempting to send.
Warming up a dedicated IP
When you acquire a new dedicated IP, it comes with no established sending history or reputation. It's like a blank slate. You must "warm up" this IP address to build trust with ISPs and prove you are a legitimate sender. This process involves gradually increasing your sending volume over time, starting with small, highly engaged lists.
There's no single universal ramp-up plan that fits all scenarios, as it depends on your target ISPs, the quality of your list, and the type of emails you send. However, the general principle is to start slow and steadily increase volume while observing deliverability metrics. Even if your domain has a strong reputation, you'll still need to warm up the new IP-domain combination.
Begin by sending your best, most engaged mail. Focus on recipients who are highly likely to open and interact with your emails. This positive engagement signals to ISPs that your mail is wanted, helping to build a good reputation quickly. For more detailed strategies, consider AWS's guidance on dedicated IP warming.
Typical warming schedule
This is a general guide and should be adapted based on performance.
Day 1-3: Send 50-100 emails per ISP, targeting most engaged recipients.
Week 1: Increase volume by 10-20% daily, staying within 1,000-5,000 emails/day per ISP.
Week 2: Double volume every few days, aiming for 10,000-25,000 emails/day per ISP.
Week 3-4: Continue gradual increase, approaching desired daily send volume. Be mindful of volume strategy.
Ongoing maintenance strategies
Once your dedicated IP is warmed up, maintaining its reputation requires consistent effort. The goal is to send a steady volume of wanted email. Spikes or drops in volume can trigger ISP filters, so strive for predictability in your sending patterns. Aim for at least 50,000 emails per day, three days a week, for optimal maintenance, although this can vary.
Recipient engagement is paramount. ISPs, particularly major ones like Google and Microsoft, extensively monitor how recipients interact with your emails. This includes opens, clicks, replies, and emails moved to the inbox, as well as negative signals like spam complaints, deletes without opening, and emails moved to the junk folder. Focus on sending relevant, timely content to engaged subscribers.
List hygiene is non-negotiable. Regularly clean your email lists to remove inactive, invalid, or problematic addresses. High bounce rates, especially hard bounces, can severely damage your IP reputation and lead to getting listed on a blocklist or blacklist. Implementing a double opt-in process for new subscribers is an excellent preventative measure against spam traps and unengaged users.
Monitoring and troubleshooting
Monitoring your IP reputation is an ongoing task. Leverage tools like Google Postmaster Tools for insights into your sending reputation with Gmail and Yahoo mail. These tools provide data on spam rates, IP reputation, domain reputation, feedback loops, and more, which are invaluable for proactive management. Additionally, regularly check major blocklists (or blacklists) to ensure your IP hasn't been listed.
Be prepared to troubleshoot. If you notice a sudden drop in deliverability or an increase in bounce rates, investigate immediately. This could be due to a spike in complaints, an unmanaged increase in volume, or issues with your email content. Address the root cause swiftly to prevent long-term damage to your IP reputation. Remember, even with a warm domain, an IP/domain combination might need its own warm-up.
Monitoring metrics
Key metrics to monitor for your dedicated IP health.
Spam complaint rate: Keep this as low as possible, ideally below 0.1%.
Bounce rate: High bounce rates, especially hard bounces, indicate poor list quality.
Open and click-through rates: High engagement signals good content to ISPs.
In addition to these quantitative metrics, pay attention to ISP feedback loops. Many major ISPs, including Gmail, Yahoo!, and Outlook.com, offer these services that notify you when subscribers mark your emails as spam. Subscribing to and acting on these reports is vital for maintaining a good sender reputation.
Final thoughts on long-term health
In summary, maintaining a dedicated IP reputation is an ongoing commitment to best practices. It's not just about the initial warm-up, but consistent sending habits, rigorous list hygiene, strong authentication, and continuous monitoring. By focusing on delivering value to engaged recipients and swiftly addressing any issues, you can ensure your dedicated IPs remain trusted by ISPs.
Remember, ISPs like Google and Microsoft are increasingly looking beyond just IP reputation to broader sender signals, including authentication protocols like SPF, DKIM, and DMARC. A holistic approach to your email program will yield the best deliverability results.
Views from the trenches
Best practices
Always warm up new dedicated IP addresses gradually to build trust.
Maintain consistent sending volumes to prevent reputation degradation with ISPs.
Focus on excellent recipient engagement to positively influence reputation.
Prioritize sending high-quality mail, especially during initial warm-up phases.
Continuously monitor your sending history and trends for each mailstream.
Common pitfalls
Expecting a new dedicated IP to instantly have a strong sending reputation.
Sending from IP space associated with low-quality or cheap VM providers.
Failing to warm up the specific IP/domain combination, even if both are individually warm.
Promising clients unrealistic deliverability outcomes without sufficient data.
Neglecting to segment transactional and marketing emails on separate IPs.
Expert tips
IP reputation is less critical than it once was, but still holds weight with major ISPs like Microsoft.
For high volumes (over 1M/day), a dedicated IP is generally recommended for more control.
ISPs with integrated webmail and mobile clients are more likely to track granular engagement.
Understand that multiple reputation systems (IP, domain) operate together.
User behavior can be unpredictable, so focus on foundational good sending practices.
Expert view
Expert from Email Geeks says IP reputation is not as important as it once was, and filters are better at stratifying based on sender size. Shared IPs are suitable for most unless they send at least a million emails a day, while a dedicated IP typically requires at least 50,000 emails per day, three days a week.
2021-01-06 - Email Geeks
Marketer view
Marketer from Email Geeks says for providers like Microsoft and T-Online, where IP reputation still matters, the overall quality of the IP space is crucial. Avoid sending from dedicated IPs associated with low-quality or cheap virtual machine providers, as this can negatively impact your standing regardless of volume.
Google and 
Microsoft, extensively monitor how recipients interact with your emails. This includes opens, clicks, replies, and emails moved to the inbox, as well as negative signals like spam complaints, deletes without opening, and emails moved to the junk folder. Focus on sending relevant, timely content to engaged subscribers.
Gmail and 
Yahoo mail. These tools provide data on spam rates, IP reputation, domain reputation, feedback loops, and more, which are invaluable for proactive management. Additionally, regularly check major blocklists (or blacklists) to ensure your IP hasn't been listed.
