Deliverability & the inbox
Shared IP
Also known as: shared sending IP · shared IP pool
A sending IP used by many brands through an ESP — the pooled reputation averages engagement signals across all senders on the IP. No warm-up required, but individual brand reputation can be damaged by co-tenants' mistakes.
A shared IP is a sending infrastructure an ESP shares across many customers. The reputation is averaged across all the senders on the pool. Pros: no warm-up required (the pool has established reputation), suitable for low-volume senders who can't maintain a dedicated IP's engagement signals, cheaper. Cons: co-tenant risk — if another brand on your shared pool sends spam, your deliverability can take collateral damage. Most ESPs segment shared pools by sending reputation tier so high-engagement senders are pooled together, which mitigates but doesn't eliminate co-tenant risk. For most programs sending under 50K/month per mailbox provider, shared IPs are the right choice.