Definition
IP reputation is the receiver’s view of traffic originating from a sending IP. Providers can consider volume, complaint rate, invalid recipients, spam-trap activity, authentication, consistency, and evidence of compromise.
A shared IP carries traffic from several customers, while a dedicated IP is controlled by one sender. Dedicated does not automatically mean better: it also means the sender must create and maintain enough clean, steady traffic to establish useful history.
Why it matters
The IP is visible at the SMTP connection, before the receiver evaluates much of the message. Poor IP history can lead to throttling or blocking, but domain and recipient-level reputation remain important too.
How it works
- 01
The receiver observes the connecting IP and reverse DNS.
- 02
It compares current traffic with the IP’s history and expected volume pattern.
- 03
It combines IP signals with authenticated domains and message-level evidence.
- 04
It decides whether to accept, defer, reject, or subject the message to additional filtering.
Common mistakes
- Buying a dedicated IP before sending enough consistent volume to operate one.
- Warming an IP with unengaged or old contacts.
- Assuming an IP lookup can explain every domain-specific delivery problem.
- Moving traffic abruptly between infrastructure without monitoring receiver response.
Key takeaways
- A dedicated IP gives control and responsibility, not automatic trust.
- Stable, wanted volume is the foundation of healthy IP history.
- Always evaluate IP and domain reputation together.