Dedicated vs Shared Sending IP: When to Actually Switch

Whether you should move to a dedicated sending IP comes down to a single number: your sustained daily volume to each mailbox provider. Not your budget, not your brand, not whatever your ESP's sales team calls its "premium" tier. If you take one thing from this article, take this — a dedicated IP under-fed with thin, bursty traffic delivers worse than a well-run shared pool, because to Gmail and Microsoft it looks exactly like a snowshoe spammer renting a fresh IP to shed a bad reputation.

The "dedicated equals better" instinct is backwards for most senders. A dedicated IP means you own the reputation — all of it, good and bad — but reputation only exists when there's enough consistent signal to build it. Below the reputation floor, a dedicated IP's history is too sparse to read, so the filters default to suspicious. You inherit the full downside of ownership with none of the volume that makes ownership pay off.

The number that actually decides this

The working threshold, as of 2026, is roughly 50,000–100,000 messages per day sustained — call it 1.5M–3M a month — before a dedicated IP is viable across the major providers. That figure isn't arbitrary. Gmail and Microsoft build a per-IP reputation model from rolling windows of traffic. Feed them a steady, predictable stream and the signal stabilizes. Feed them 3,000 messages on Tuesday, nothing Wednesday, a 40k campaign Friday, and the model never converges — every send looks like a fresh pattern to evaluate from cold.

The per-provider corollary matters more than the aggregate. You need roughly 5,000+ messages per day, consistently, to each of your top mailbox providers