A shared IP is a sending IP address used by many customers of the same email platform. Their emails go out through a common pool of IPs, and the reputation of each IP reflects the combined behaviour of everyone sending through it. Most small and mid-sized senders use shared IPs, often without realising it.
Shared IPs suit lower or irregular volumes. A business sending 20,000 emails a month can’t build a strong reputation on an IP of its own, because providers need regular volume to judge it. On a shared pool, the combined volume of many good senders keeps the IPs warm and established, so even a small sender benefits from a reputation it couldn’t build alone.
The risk is that other senders on the same IPs can affect you, the so-called noisy neighbour problem. A responsible platform manages this by vetting new customers, monitoring bounce and complaint rates, pausing accounts that cross limits and sometimes separating senders into pools by quality. How well the platform does this matters more than the shared-or-dedicated choice itself.
Keep in mind that domain reputation is yours even on a shared IP. Mailbox providers increasingly judge mail by the authenticated domain, so a careful sender on a shared IP can still build an excellent reputation of its own by authenticating properly and sending only wanted mail.
A Hyderabad dance academy sends a monthly newsletter to 3,500 parents and a few event reminders. On a dedicated IP, its small, uneven volume would never build a reputation. On its platform’s shared pool, its emails go out through warm, established IPs, and its own authenticated domain builds a good record over time.