IP pools
Which IPs your mail leaves from, how an account moves from the warm-up pool to the shared pool, and when a dedicated IP is worth buying.
Mailbox providers judge a sender first by the reputation of the IP the mail arrived from. Every Mailfully account sends from a pool of managed IPs, and which pool you are on is decided for you, then re-checked daily. There is nothing to configure and nothing in the API that selects a pool.
The pools
| Pool | Who sends from it |
|---|---|
| Warm-up | New accounts, and any account currently throttled or paused |
| Shared | Accounts with an established, clean sending record |
| Dedicated | Accounts on the dedicated-IP add-on |
Warm-up
Every account starts here. The IPs in this pool are warmed adaptively, so a new sender's first messages ride on IPs that already have standing rather than on a cold address with no history. A struggling account is moved back here, which keeps a bad list from spending down the reputation the established pool has built. See Warming up a new domain for the ramp to follow on your side while an account sits in this pool.
Shared
An account graduates to the shared pool on its own once it has a track record: a verified sending domain, account age, sustained volume, and bounce and complaint rates well inside the ceilings on Policies. A verified domain is required — no amount of clean volume graduates an account that has not verified one. See Verify a domain.
Graduation is not permanent. If your rates degrade far enough that the account is throttled or paused, the next daily re-check puts you back on the warm-up pool. Fixing the underlying list moves you forward again on the same schedule.
Dedicated
A dedicated pool holds IPs nobody else sends from, so no other sender's mistakes can affect your reputation.
A dedicated IP is a $29/month add-on on any paid plan. A Scale subscription started before October 19, 2026 includes one. There is no self-serve toggle; contact support to have one provisioned. Once it is in place the dedicated pool takes precedence over everything above, including the daily re-check — a dedicated account is never moved to the warm-up pool.
A dedicated IP is worth it at consistent volume, not at low volume. Mailbox providers build trust from a steady stream; a dedicated IP that sends a few hundred messages a week never accumulates enough signal, and sporadic traffic from an unfamiliar IP reads worse than the same traffic from a busy shared one. If your volume is not steady and in the thousands per day, the shared pool will deliver better.
A new dedicated IP is ramped rather than opened at full volume, so plan for the ramp before you move a large existing list onto one.
When a change takes effect
Pool assignment is recomputed daily and applied to your account's sending configuration. A change is invisible from your side: the from address, the DNS records, and every API call stay exactly as they are, and messages already queued are unaffected. Expect a move — in either direction — to land within a day of the reputation change that caused it.
What actually moves the needle
Authentication (DKIM, SPF, and DMARC), honest opt-in, prompt suppression handling, and steady volume decide delivery on every pool. The thresholds you are measured against, and what happens when you cross them, are on Policies.