Definition
A shared IP address is used by multiple senders — often hundreds or thousands — managed by an email service provider (ESP). The sending reputation of the IP is determined by the collective behaviour of all senders using it. If one sender generates high spam complaints, it negatively affects deliverability for everyone else on that IP.
Shared IPs are the default for most ESPs and are well-suited for small to medium senders, low-volume programmes, and new senders who have not yet established their own reputation. The ESP monitors and manages shared IP pools, removing problematic senders to protect overall deliverability.
Shared vs Dedicated IP
| Factor | Shared IP | Dedicated IP |
|---|---|---|
| Cost | Included in ESP plan | Additional fee |
| Volume suitability | Low to medium | Medium to high |
| Reputation control | Shared with others | Full control |
| Warming required | No (pool is warm) | Yes (2–6 weeks) |
| Recovery from issues | ESP manages pool | Self-managed |
Best Practices
- Choose an ESP with rigorous sender vetting for their shared pools
- Monitor your own reputation even though the IP is shared
- Request a dedicated IP if your volume exceeds 100,000 per month
- Avoid sending from shared IPs in bulk to unknown or purchased lists
- Understand your ESP's abuse management policies for the shared pool
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 PTR Record
PTR record (reverse DNS) for email sending. How PTR records work, why mailbox providers require them for dedicated IPs, format requirements, setup checklist, and troubleshooting.
Email Sender Infrastructure
Email sender infrastructure architecture covering sending domains, subdomains, dedicated versus shared IPs, tracking domains, and return-path domains.
Frequently Asked Questions
Yes — if the shared IP pool is well-managed by the ESP. High-quality ESPs actively monitor shared pools, remove abusive senders, and maintain strong relationships with mailbox providers. For low to medium volume senders, well-managed shared IPs often perform as well as dedicated IPs.
Your deliverability drops until the ESP removes the problematic sender. This is the key risk of shared IPs — you have no control over who shares your IP. Reputable ESPs monitor and act quickly, but there is always some risk of collateral damage.