Guide
Email Warmup: Schedule, Settings & Tools
Email warmup builds sending history for a new inbox by starting with a few emails a day and increasing slowly over 2–4 weeks. Here's the schedule, the settings to use, the tools, and when to skip it.
Health
92%
Today
10 sent
Reply rate
30%
Warmup emails per day, first 10 days · +1 a day
Ready for campaigns in 4 days
Basics
What is email warmup and how does it work?
Mailbox providers trust senders with a history. A new inbox has none, so email warmup creates one: low volume first, real engagement, then gradual growth.
Step 1
Connect
Link the inbox to a warmup tool, ideally by OAuth.
Step 2
Join a pool
It trades emails with other inboxes in the tool's network.
Step 3
Engage
Warmup emails are opened, replied to and pulled out of spam.
Step 4
Ramp up
Daily volume grows a little each day to a set limit.
Step 5
Send
Cold emails start low and grow while warmup keeps running.
Google's own sender guidelines say the same thing in plainer terms: start with low volume, increase it slowly, and avoid sudden spikes if you don't have a history of sending. Warmup can't fix broken authentication or a bad list, so check those first with the SPF checker and the deliverability guide.
Schedule
How to warm up an inbox, week by week
Our suggested schedule for a new Google or Microsoft inbox on a new cold email domain. Warmup runs the whole time; cold volume grows weekly.
Cold emails per day from one new inbox
Jetmail's recommendation, 5 sending days a week. Stricter teams run 2 weeks of warmup only (as Instantly suggests) before week 1.
| Week 1 | 5 |
|---|---|
| Week 2 | 10 |
| Week 3 | 20 |
| Week 4+ | 30 |
| Week | Cold emails / day | Warmup | Check before moving on |
|---|---|---|---|
| Week 1 | 5 | On, rising about 1 a day | SPF, DKIM and DMARC all pass |
| Week 2 | 10 | On | No bounces from bad addresses |
| Week 3 | 20 | On | Inbox placement test lands in the inbox |
| Week 4+ | 30 | On, at a low level | Spam complaint rate under 0.1% in Postmaster Tools |
The same steps work to warm up a Gmail (Google Workspace) account or a Microsoft 365 mailbox. To warm up a cold email domain, warm up every inbox on it together and keep each one at the same pace. Picking domains? See cold email domains.
Warmup vs pre-warmed
Warm up inboxes yourself or buy them pre-warmed?
A warmed inbox is the goal either way. The difference is who spends the weeks getting there.
| Warm up a new inbox | Pre-warmed inbox | |
|---|---|---|
| Before full volume | 2–4 weeks | Day one |
| First-month cold emails | 385 | 660 |
| Price per inbox (Growth) | $3.30 / month | $12.42 first month, then $7.00 |
| Main risk | Sending too much too soon during the ramp | Same list and content rules as any inbox |
| Warmup tool | Needed throughout | Keep running at a low level |
| Best for | Long-running programs with time to spare | Launches, new clients, replacing burned inboxes |
Skip the warmup weeks
Tools
Best email warmup tools compared
Prices from each vendor's site, checked October 2026, monthly billing. Confirm on their site before buying.
| Tool | Price | Free option | Notes |
|---|---|---|---|
| Instantly | In plans from $47/mo | 14-day trial | Unlimited accounts and warmup on every plan |
| Smartlead | In plans from $39/mo | Free trial | Warmup pool tier rises with the plan |
| lemwarm | $29/mo per address | Included in every lemlist plan | Essential plan, monthly billing |
| Warmup Inbox | $19/mo per inbox | Freemium: 15 warmup emails a week | Basic plan, monthly billing; 7-day trial |
| MailReach | $19.50/mo per mailbox | Free spam test | Includes spam test credits |
Extra monthly cost of warmup, per inbox
Monthly billing, October 2026. Instantly and Smartlead include warmup in their sending plans, so it adds nothing per inbox.
| Instantly | Included |
|---|---|
| Smartlead | Included |
| lemwarm | $29 |
| Warmup Inbox | $19 |
| MailReach | $19.5 |
Warmup networks depend on mailbox providers tolerating them. GMass shut down its free warmup tool in January 2023, saying Google had told it to stop. That's one reason to treat warmup as a support for good sending, not a substitute for it. Using Instantly or Smartlead? Their built-in warmup settings are covered on those pages. For a longer side-by-side, see the best email warmup tools comparison.
Checklist
Email warmup checklist
- Publish SPF, DKIM and DMARC before the first warmup email.
- Connect each inbox to one warmup tool, not several at once.
- Ramp warmup by about 1 email a day, up to around 10 a day for a new inbox.
- Keep reply rate near 30% and warmup running after campaigns start.
- Add cold emails slowly: 5 → 10 → 20 → 30 a day, week by week.
- Run an inbox placement test before scaling, and pause any inbox that starts landing in spam.
Building the whole setup? Start with cold email infrastructure.
Sources: Google email sender guidelines · Instantly: how warmup works · Instantly: warmup settings · Instantly pricing · Smartlead API: warmup guide · Smartlead pricing · lemwarm pricing · Warmup Inbox pricing · MailReach pricing · GMass: warmup shutting down
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Or see pricing →Frequently asked questions
What is email warmup?
Email warmup is building a sending history for a new mailbox or domain before you send cold email from it. You start with a few emails a day and increase slowly, usually with a warmup tool that trades emails with other mailboxes and opens and replies to them.
How long does it take to warm up an inbox?
Two to four weeks for most new inboxes. Instantly recommends at least 2 weeks and a warmup health score above 90% before campaigns; Smartlead's API guide says at least 14 days, and 21–30 days for newer domains.
Is there a free email warmup tool?
Yes. As of October 2026, Warmup Inbox has a free plan with 15 warmup emails a week, and warmup is included at no extra cost in sending tools such as Instantly, Smartlead and lemlist.
How do I warm up a Gmail account?
Connect the Google Workspace mailbox to a warmup tool by OAuth, let warmup ramp up by about 1 email a day to around 10 a day (Instantly's defaults for new accounts) and keep it running for 2+ weeks. Then add cold emails slowly, starting around 5 a day.
How do I warm up a new cold email domain?
Publish SPF, DKIM and DMARC, redirect the website to your main site, then warm up every mailbox on the domain at the same time. Keep cold volume low for the first few weeks and spread it across mailboxes rather than pushing one.
Do I need warmup if I buy pre-warmed inboxes?
You skip the waiting period, but keep a warmup tool running at a low level alongside your campaigns so engagement stays steady.