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, and every Scale account |
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.
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 your reputation is entirely your own and no other sender's mistake can reach it. The reverse is also true: nothing absorbs your own mistakes.
Scale bundles one dedicated IP. On Starter and Growth it is a $29/month add-on. 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, because its reputation is already isolated.
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
The pool is downstream of your sending, not a substitute for it. Authentication (DKIM, SPF, and DMARC), honest opt-in, prompt suppression handling, and steady volume decide delivery on any pool. The thresholds you are measured against, and what happens when you cross them, are on Policies.