Definition
An IP pool is a collection of dedicated IP addresses managed as a group for sending email. Instead of sending all email traffic from a single IP, senders distribute volume across multiple IPs in the pool, reducing the impact of any single IP's reputation issues and providing capacity for high-volume sends.
IP pools are commonly used by enterprise senders to separate different types of email traffic — marketing, transactional, and corporate communications — onto different pools so that a marketing campaign's reputation issues do not affect transactional email deliverability. Each pool can also be warmed independently.
IP Pool Strategies
| Strategy | Description | Best For |
|---|---|---|
| Single pool | All traffic from one pool | Low-volume, simple programmes |
| Segmented pools | Different pools per email type | Separating marketing from transactional |
| Warm pool + new pool | Established pool for regular volume, new pool for warming | Scaling sending capacity |
| Seasonal pool | Additional pool for peak volume | Holiday retail, flash sales |
Best Practices
- Separate marketing and transactional email onto different IP pools
- Warm each IP in a pool individually before adding it to rotation
- Monitor reputation per IP pool, not just aggregate
- Maintain spare capacity in your pool for volume spikes
- Use a pool large enough to absorb a single IP being removed (quarantined)
- Document your IP pool strategy including fallback plans for reputation issues
- Work with your ESP to configure and manage pool routing
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Related Glossary Terms
Dedicated IP
A dedicated IP is an internet protocol address assigned exclusively to a single sender, giving them full control over their sending reputation without influence from other senders sharing the same address.
Email Sending IP
Dedicated vs shared IP pools for email sending, IP reputation scoring, warmup process (4-8 weeks), rotation strategies, and IPv6 considerations for optimal deliverability.
Email Sending Domain Strategy
The practice of using multiple sending subdomains for different email types to isolate reputation, protect deliverability, and improve inbox placement.
Email Sending Reputation Monitoring
The ongoing process of tracking sender score, domain reputation, IP reputation, and feedback loop data across ISPs to detect and respond to deliverability changes.
SMTP Settings
SMTP settings are the server configuration parameters — host, port, username, password, encryption — required to connect an email client or application to an SMTP server for sending outgoing email.
Email Spam Filter Tuning
The process of adjusting email content, sending patterns, and infrastructure to improve inbox placement by adapting to current spam filter algorithms.
Frequently Asked Questions
The right pool size depends on your sending volume. A common starting point is 3–5 IPs per pool for programmes sending 500,000–2,000,000 emails per month. Higher volumes need larger pools. The goal is to distribute volume so that no single IP exceeds 100,000–200,000 sends per day.
No. Every IP added to a pool — even an existing warm pool — must be warmed gradually. Cold IPs added to a pool receiving high volume will trigger throttling and blocking from mailbox providers. Warm each new IP over 4–6 weeks before allowing full volume.