How do shared IPs affect reputation?

Shared IPs create interdependent reputation. Every sender using that address contributes to a collective trust score that affects everyone in the pool.

When the pool is healthy, shared IPs often provide better deliverability than a new sender could achieve alone. The accumulated trust from many senders creates a strong baseline. Reputable ESPs maintain high standards for who can access their shared pools.

The risk is bad neighbors. A single sender generating complaints, hitting spamtraps, or sending spam can drag down the entire pool. This is why ESP enforcement and sender vetting matters so much for shared infrastructure.

Shared IPs are apartment buildings of the email world. A well-managed building with good tenants is pleasant. One disruptive neighbor can make life difficult for everyone until management intervenes.