Email Warmup Calculator
This email warmup calculator plans how a new mailbox ramps up to its daily sending target. Choose a start volume, a target and a pace, and get a day-by-day schedule with weekly totals. Then enter the total you want to send to see how many mailboxes and domains you need. The paces and limits come from published vendor and provider guidance.
Plan your ramp. See when you reach full volume.
100% free • No signup • Runs in your browser
Day 8: you reach 30 emails a day (149 emails sent while ramping)
| Week | Emails a day | Week total |
|---|---|---|
| Week 1 | 10, 12, 14, 16, 19, 22, 26 | 119 |
| Week 2 | 30 | 30 |
At 30 a mailbox, that's 10 mailboxes. If your domains are under a month old, spread them over at least 3 domains: lemlist keeps a new domain under 100 emails a day across all its mailboxes.
How to use the Email Warmup Calculator
- 1
Set your numbers
Pick your email provider, how many emails to send on day 1, and the daily target for each mailbox.
- 2
Choose a pace
Ramp by one email a day, or by 10% or 20% a day. The chart and weekly table update as you change them.
- 3
Plan your mailboxes
Enter the total you want to send a day to see how many mailboxes, and new domains, that takes. Download the schedule as a CSV.
What cold email tools recommend
This is vendor advice, not a provider rule, and it varies. Pick a pace you can hold, and slow down if replies drop or bounces rise.
| Vendor | Cold emails a day | Warmup |
|---|---|---|
| Instantly | 30 to 50 emails per mailbox. Source | At least 2 weeks; warmup starts at 1 email and adds 1 a day. Source |
| lemlist | 30 to 40 per mailbox once stable; a domain under a month old stays under 100 a day. Source | About 40 days at +1 a day, then 14 days steady. Source |
| Smartlead | 30 to 50 for a fresh mailbox in its first 30 days. Source | At least 2 weeks of warmup before 100 to 150 a day. Source |
| Woodpecker | No more than 100 a day, whatever the provider allows. Source | 3 to 4 weeks for a new mailbox, 2 to 3 months for a new domain. Source |
| MailReach | Around 100 per address over the long term. Source | Start at 15 to 20 a day over 3 to 4 weeks; never more than 20% a day. Source |
Provider sending limits
- Google Workspace: 2,000 messages a day per user (500 on trial accounts). Source
- Microsoft 365: 10,000 recipients a day and 30 messages a minute. Source
- Free Gmail: About 500 emails a day. Source
Warming up is half of it; the other half is what you send. Check your copy with the Email Spam Checker and clean your list with the Email Checker before you launch.
Frequently Asked Questions
How long should I warm up a new email account?
Vendors disagree. Instantly says at least two weeks, lemlist ramps for about 40 days, and Woodpecker suggests three to four weeks for a new mailbox and two to three months for a new domain. Google gives no number: it says to start low with engaged recipients and increase slowly.
How many cold emails can I send a day per mailbox?
Most cold email tools recommend about 30 to 50 a day for a new mailbox (Instantly, lemlist, Smartlead). That's far below Google Workspace's 2,000-a-day limit, because those limits are ceilings for normal email, not safe cold email volumes.
What are Gmail's and Outlook's sending limits?
Google Workspace allows 2,000 messages a day per user (500 on trial accounts), and free Gmail about 500. Microsoft 365 allows 10,000 recipients a day and 30 messages a minute. Go over Gmail's limit and you can't send again for 1 to 24 hours.
Is it safe to double my sending volume?
No. Google warns that suddenly doubling volume can lead to rate limiting or reputation drops. MailReach advises never increasing by more than 20% in a day, which is the fastest pace in this calculator.
What should I set up before warming up?
SPF, DKIM and DMARC on your sending domain. Gmail and Yahoo require SPF or DKIM from every sender, and SPF, DKIM and DMARC from bulk senders. Keep spam complaints below 0.3%.
Why use several mailboxes instead of one?
Each mailbox stays at a safe daily volume, and one problem doesn't stop all your sending. Spread them over more than one domain, especially new ones: lemlist keeps a domain under a month old below 100 emails a day.