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Warm up new mailboxes and domains

Workflow Reviewed · not yet fact-checked

In short

How do I warm up new mailboxes and domains in Reply before cold outreach?

Authenticate the domain first, then warm each mailbox in MailToaster for two to three weeks (one to two for a new mailbox on an established domain) using a warm-up profile, then start cold volume with ramp-up mode — 10 emails per day rising by 3 to 100 by default — and keep warm-up running throughout.

At a glance

AspectDetail
OutcomeA new domain and its mailboxes authenticated, warmed, and ramping to full sending volume without burning sender reputation
Required objectsA domain with DNS access; connected email accounts; a MailToaster warm-up seat per mailbox
SurfacesUI · REST API · MCP
Key limitRoughly 2–3 weeks of warm correspondence for a new domain (1–2 weeks for a new mailbox on an established domain) before cold outreach; ramp-up default 10 emails per day, +3 daily, to 100
Stops onRamp-up stops with a notification once the account's total email limit is reached; warm-up connect and the Activate toggle fail with an error when no warm-up seats are free
Does notMake a fresh domain safe on day one — no setting skips the calendar; replace DNS authentication — warm-up builds reputation on top of correct records, not instead of them; send warm-up traffic itself through ramp-up, which only raises real sending volume
PlansMailToaster comes with a paid Reply subscription — one warm-up seat per connected mailbox; the MailToaster instance is shared per workspace

Goal

Every new email account reaches its working daily volume through three ordered layers: authenticated DNS, several weeks of simulated positive engagement (warm-up), and a gradual increase of real sending (ramp-up) — with warm-up still running once cold email flows. The mechanism behind the ordering is explained in Email warm-up and Sender reputation.

When to use this workflow

Any time sending will start from infrastructure that mailbox providers have never seen: a newly registered domain, new mailboxes on an existing domain, or domains and mailboxes purchased through Reply. If the domain is established and actively sending, only the new mailbox needs the 1–2 week warm-up window.

What Reply provides

MailToaster warm-up with no separate account — you are signed in through your Reply session, every workspace gets its own shared instance, and each connected mailbox gets one warm-up seat. Per-mailbox warm-up profiles, daily goals, and cleanup run from the mailbox's WarmUp tab in Reply. Ramp-up mode is built into every email account's Safety settings and is on by default for newly added accounts. The weekly domain Health Checker verifies the DNS layer — see Deliverability.

What you must provide

DNS access at your domain host, the warm-up patience (the weeks are the mechanism, not an inconvenience), and — if you hand-send warm correspondence — real positive interactions: opens, replies, not-spam rescues, forwards, across a variety of providers such as Gmail, Outlook, and Yahoo. Deleting, opting out, or spam-flagging by your warm contacts works against you.

Preconditions

A domain with editable DNS; mailboxes you can authenticate (Gmail warm-up needs two-factor authentication and an app password; Outlook connects to warm-up automatically; Exchange Single Click and On-Premises mailboxes are not supported for warm-up); free warm-up seats.

Buying the domain and mailboxes in Reply

You can also start this workflow without owning infrastructure: the Email Accounts page has a purchase flow (beta, team owner only) that registers domains and provisions Google or Microsoft mailboxes — up to 5 per domain, connected to Reply within 48 hours. Purchased mailboxes default into MailToaster warm-up via the warm-up toggle at purchase: Google mailboxes and pre-warmed Microsoft packages enroll as soon as they are provisioned, while a regularly purchased Microsoft mailbox waits out a 4-day locked period first — its absence from MailToaster in those first days is expected. Pre-warmed packages (a domain bundled with 3 ready-to-send mailboxes) arrive already warmed. Domains are one-year purchases and do not auto-renew — an expired domain deactivates its mailboxes and removes them from warm-up.

Step-by-step flow

authenticate DNS → connect mailboxes → add to warm-up → pick profile
    → set daily goal → wait 2–3 weeks → start cold volume with ramp-up
    → keep warm-up running
  1. Authenticate the domain: MX records to receive mail, SPF, DKIM, and DMARC to pass authentication — required by mailbox providers, and by Google and Yahoo sender rules. Major providers preset A and rDNS; self-hosted servers must check them. See Set up DNS for sending.
  2. Connect the mailboxes, or purchase them through Reply as above.
  3. Add each mailbox to warm-up: Settings → Email Accounts → the mailbox's WarmUp tab → Connect, or check Import to MailToaster when adding the account. CSV bulk imports arrive with warm-up settings preconfigured and activate immediately. Procured mailboxes need no credentials at this step.
  4. Pick a warm-up profile: New email account for fresh inboxes, Reputation protect for existing ones, or a Custom profile controlling what share of warm-up emails are opened, rescued from spam, replied to, or marked important.
  5. Set the daily goal: Ramp-up mode (starting number plus a daily increment) or Random mode (a min–max range sent each day). Optionally enable Sent folder cleanup, which removes warm-up emails older than 3 days.
  6. Let warm-up run — roughly 2–3 weeks for a new domain, 1–2 weeks for a new mailbox on an established domain — before any cold sending.
  7. Start cold outreach with ramp-up mode on (it is on by default for new accounts): 10 emails per day, +3 daily, up to 100. Match the start to your warm-up volume — after finishing a 50-per-day warm-up, start around 40–45 with a ramp of 7–10; if warm-up and cold sending run simultaneously, start at 10–15.
  8. Leave the per-email delay at its default (a random 300–450 seconds on new accounts). Sequence-level speed settings exist too, but the account's Safety settings win.
  9. Keep warm-up enabled through ramp-up and after it ends, for as long as the account sends cold email.

Rules that apply

Sending schedules — when sends happen · Mailbox selection — how volume spreads across accounts · Bounce handling — the 4% and 8% thresholds that protect a ramping account · The account daily limit always caps the sequence's own limit — see Configure sending limits.

Failure conditions

  • No free warm-up seats — Connect and the Activate/Pause toggle fail with a seat-count error until the subscription adds seats
  • Exchange Single Click and On-Premises mailboxes cannot join MailToaster warm-up
  • A regularly purchased Microsoft mailbox is missing from MailToaster during its first 4 days — expected, not a failure
  • Procured-mailbox reconnects are rate-limited: 7 attempts per 7 days per mailbox, with a 60-minute cooldown between manual attempts
  • Raising volume too fast after warm-up — the documented outcome is deliverability trouble; ramp-up exists to prevent exactly this

Verification

Hover the fire icon on the email account to see the current ramp-up state without opening the Safety tab. Warm-up activity shows per mailbox in MailToaster; the domain Health Checker refreshes weekly with per-record status. A test send to your own address should land in the inbox, not spam.

Limits

LimitValue
Warm correspondence before cold outreach~2–3 weeks for a new domain; 1–2 weeks for a new mailbox on an established domain
Ramp-up defaultStart 10 emails per day, +3 daily, up to 100
Default delay between emails (new account)Random 300–450 seconds
Account daily maximum400 emails on paid plans, 200 on trial
Sequence Max emails per dayCannot exceed the account's own daily limit
Warm-up seatsOne per connected mailbox; no free seat blocks connect
Sent folder cleanupRemoves warm-up emails older than 3 days
Regular Microsoft procured mailbox4-day lock before warm-up enrollment
Procured-mailbox reconnect7 attempts per 7 days; 60-minute manual cooldown

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