For many organizations, managing email deliverability effectively requires a keen understanding of IP addresses, particularly when scaling email operations. The choice between shared and dedicated IPs is crucial, but for high-volume senders, the question often shifts from if they need a dedicated IP to when they need multiple dedicated IPs.
The core of the issue often lies in balancing send volume, desired delivery speed, and maintaining a pristine sender reputation. While a single dedicated IP can handle significant volume, there comes a point where adding more dedicated IPs becomes not just beneficial but necessary to overcome rate limiting, enhance throughput, and safeguard your sender reputation across various Mailbox Providers.
Evaluating your current sending volume
One of the primary drivers for needing more dedicated IPs is sheer email volume. While there isn't a universally fixed threshold, general guidelines suggest that if you're consistently sending several million emails per month, or over a million emails per day, you should evaluate the benefits of additional IPs.
Beyond raw numbers, the consistency of your sending volume plays a significant role. Sporadic, large bursts of email from a single IP can trigger rate limits or even land you on a blacklist (or blocklist), regardless of your total monthly volume. Consistent daily sending is key to maintaining a warm and trusted IP reputation.
Furthermore, the composition of your recipient list matters. Some Mailbox Providers have stricter rate limits than others. If your list includes a high percentage of recipients on smaller, more restrictive domains, spreading your volume across multiple IPs can help mitigate throttling and improve overall delivery speed.
Monthly Volume (approx.)
Daily Volume (approx.)
Recommended Dedicated IPs
Under 100,000
Under 3,000
Shared IP (or 1 dedicated, if consistency is high)
100,000 - 1,000,000
3,000 - 30,000
1 Dedicated IP
1,000,000 - 30,000,000
30,000 - 1,000,000
1-2 Dedicated IPs
Over 30,000,000
Over 1,000,000
2+ Dedicated IPs
Reputation and deliverability
Your sender reputation is intricately linked to your IP addresses. On a single dedicated IP, all your sending behavior is concentrated, meaning any negative signals, like high bounce rates or spam complaints, can quickly degrade its reputation. This can lead to increased rate limiting, delayed delivery, or even email rejection by Internet Service Providers (ISPs).
Distributing your email volume across multiple dedicated IPs can help compartmentalize your sending reputation. If one IP experiences a temporary dip due to a specific campaign, your other IPs might remain unaffected, ensuring consistent deliverability for other email streams. This strategy offers a buffer against isolated reputation issues.
However, it is important to remember that domain reputation is increasingly becoming the primary factor for many Mailbox Providers. While IP reputation is still vital, a strong domain reputation can often outweigh minor IP issues, especially with major providers like Gmail. Therefore, focusing on content quality and list hygiene remains paramount, regardless of your IP strategy.
Reputation is complex
Sender reputation is influenced by a multitude of factors, not just IP address. These include your email content, spam complaint rates, bounce rates, subscriber engagement, and authentication protocols like DMARC, SPF, and DKIM. Neglecting these areas can lead to deliverability issues even with multiple dedicated IPs.
Strategic advantages of multiple IPs
For very large sending volumes, it may become necessary to use multiple dedicated IPs to handle the load. This is especially true if you are experiencing consistent rate limiting or delays from ISPs. While Mailbox Providers often focus on domain reputation, IP reputation still plays a significant role in determining how quickly and reliably your emails are accepted.
One strategic benefit of multiple IPs is the ability to segment your email traffic. You might designate one IP for transactional emails, which typically have very high engagement and low complaint rates, and another for marketing or promotional emails, which might carry a slightly higher risk of negative feedback. This segmentation can protect the deliverability of your most critical communications.
Additionally, multiple IPs can offer a degree of redundancy. If one IP somehow gets temporarily blocklisted (or blacklisted), your other IPs can continue sending, minimizing disruption to your email program. This adds a layer of resilience to your deliverability strategy.
Single dedicated IP challenges
Reputation Risk: All sending behavior concentrated on one IP, making it vulnerable to rapid degradation if issues arise.
Throughput Limitations: Can experience rate limiting or slower delivery speeds when sending extremely high volumes or to diverse Mailbox Providers.
Reputation Segmentation: Allows for separation of email streams (e.g., transactional vs. marketing) to isolate reputation.
Enhanced Throughput: Distributes volume, potentially speeding up delivery, especially to smaller ISPs or those with stricter connection limits.
Improved Redundancy: Provides backup sending capacity if one IP encounters deliverability issues, ensuring continuity.
Managing multiple dedicated IPs
Moving to multiple dedicated IPs, or adding new ones, requires a careful warming process. Each new IP must build its reputation gradually by sending low volumes of highly engaged emails, slowly increasing the volume over weeks. Neglecting this step can lead to poor deliverability and wasted investment.
Continuous monitoring of all your dedicated IPs is essential. This includes tracking inbox placement rates, monitoring for rate limits, and checking if any IPs land on a blacklist (or blocklist). Tools and services specializing in IP and domain reputation monitoring can provide the insights needed to react quickly to any issues.
It's important to align your IP strategy with your ESP's capabilities. Some ESPs provide advanced features for managing multiple IPs, including automated volume distribution and reputation management. Others might prefer a single dedicated IP for certain volumes, even if you feel more are needed.
Open communication with your ESP about your sending patterns, growth plans, and deliverability concerns is vital. They are your partner in ensuring optimal performance and can advise on the best IP setup for your specific needs.
Final considerations
The decision to acquire more dedicated IPs depends on a confluence of factors: your total email volume, the consistency of your sending, the diversity of your recipient Mailbox Providers, and your strategic goals for deliverability and redundancy.
While there are general benchmarks for when to consider multiple dedicated IPs, the most accurate assessment comes from analyzing your specific sending patterns, monitoring your deliverability metrics closely, and consulting with your ESP to ensure your IP strategy aligns with your overall email program's health and goals.
Views from the trenches
Best practices
Maintain a highly consistent sending volume across all your dedicated IPs to build and preserve a strong reputation with Mailbox Providers.
Segment your email types (e.g., transactional, marketing) and assign them to different dedicated IP pools to isolate reputation risks and optimize deliverability for critical messages.
Proactively monitor your IP and domain reputation across various ISPs using feedback loops and Postmaster Tools to identify and address issues quickly.
Regularly clean your email lists to minimize bounces and spam complaints, which are critical factors affecting both IP and domain reputation.
Common pitfalls
Assuming more IPs automatically solve deliverability issues without addressing underlying content, list quality, or engagement problems.
Failing to properly warm up new dedicated IPs, leading to immediate deliverability problems and potentially long-term reputation damage.
Ignoring Mailbox Provider-specific rate limits and policies, which can vary significantly and require tailored sending strategies.
Relying solely on IP reputation while neglecting the growing importance of domain reputation, which can lead to missed opportunities for inbox placement.
Expert tips
Consider a dedicated IP if you send over 1 million emails daily, especially to diverse Mailbox Providers, to improve delivery speed and manage throttling.
If rate limits occur, investigate whether they are reputation-based or content-based, as more IPs will not solve content-related issues.
For very high volumes (e.g., 78 million emails per month), a single dedicated IP can perform well if the list quality is high and sending is consistent.
While multiple IPs offer redundancy, a single dedicated IP can provide clearer visibility into blocklist (or blacklist) events, as issues are immediately apparent.
Expert view
Expert from Email Geeks says more IPs would help, noting their experience with 5 IPs for 15-45 million emails monthly, and queries why the ESP isn't preventing issues.
2022-01-26 - Email Geeks
Marketer view
Marketer from Email Geeks says their ESP believes only one dedicated IP is needed.
