Free tool · Shareable schedule
Warm up your mailboxes
at the right speed
New mailboxes earn trust the boring way: a little more volume every day. Plan the exact ramp — and learn where the math has to bow to the calendar.
13
days to reach target
711
emails sent during warmup
2,640
monthly capacity after
Day-by-day schedule (per mailbox)
| Day | Per mailbox | All 3 mailboxes |
|---|---|---|
| Day 1 | 5 | 15 |
| Day 2 | 6 | 18 |
| Day 3 | 7 | 21 |
| Day 4 | 9 | 27 |
| Day 5 | 10 | 30 |
| Day 6 | 12 | 36 |
| Day 7 | 15 | 45 |
| Day 8 | 18 | 54 |
| Day 9 | 21 | 63 |
| Day 10 | 26 | 78 |
| Day 11 | 31 | 93 |
| Day 12 | 37 | 111 |
| Day 13 | 40 | 120 |
The warmup rules the calculator can't bend
The calendar outranks the curve
Providers score account age, not just volume shape. A perfect ramp compressed into 8 days still reads as 'new domain in a hurry' — the riskiest profile there is.
Engagement is half of warmup
Volume without opens and replies is just noise. Real warmup needs mail that gets opened, read and answered — which is why warmup networks exchange real-looking conversations.
Warmup never fully stops
A warmed mailbox that goes quiet for two weeks cools down. Keep a baseline of activity even between campaigns, or budget a mini re-warm after every pause.
Watch bounces during the ramp
A bounce spike during warmup does double damage — the list is judging you while the providers are still deciding what you are. Verify every address before it enters a warmup-phase campaign.
Questions, answered honestly
Why do new mailboxes need warming up at all?
A brand-new mailbox has no sending history, and providers treat history as identity. Jumping from 0 to 50 emails a day looks exactly like what spammers do with fresh domains — so Gmail and Microsoft throttle or spam-folder it preemptively. Warmup builds the history gradually: small volumes, growing daily, with real-looking engagement.
How long should warmup take?
Two to four weeks minimum for a new mailbox on a new domain. Even if the math in this calculator says you could reach your target in 9 days, hold the floor at 14 — providers weight account age as well as volume curve. A domain younger than 2-3 weeks shouldn't send cold email at all.
What's a safe daily increase?
20–30% per day is the proven band. Doubling daily (100%) is how mailboxes get flagged in week one. Slower is always safe; faster is borrowing against a reputation you don't have yet.
What volume should I warm toward?
20–50 cold emails per mailbox per day. Beyond 50, the risk curve steepens fast — the scalable move is more mailboxes across more domains, each kept comfortably under the ceiling, not one hot mailbox.
Do I still need to warm up if I use Google Workspace?
Yes. The provider gives you infrastructure reputation, but your specific mailbox and your domain still start from zero. Workspace mailboxes warm faster than self-hosted SMTP, but skipping warmup entirely still gets fresh domains filtered.
Keep going
More free tools
Or skip the spreadsheet entirely.
Norbelys warms your mailboxes automatically — real ramp curves, real engagement, reputation back-off when a provider pushes back — and hands each mailbox to your campaigns only when it's ready.
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