---
title: "Email Warmup: Definition and Examples"
description: "Email warmup is the process of building a new mailbox or domain's sending reputation by starting at low volume and raising it gradually, often with..."
path: /glossary/email-warmup
family: glossary
updated: 2026-10-17
html: /glossary/email-warmup
sources:
  - "https://support.google.com/a/answer/81126"
  - "https://www.twilio.com/docs/sendgrid/concepts/reputation/warm-up-ip-addresses"
facts:
  term: "Email warmup"
  also_called: "email warm up, email warming, inbox warmup, domain warmup, mailbox warmup"
  category: "Deliverability"
---

# Email warmup

Email warmup is the process of building a new mailbox or domain's sending reputation by starting at low volume and raising it gradually, often with automated messages exchanged between real inboxes that open them, reply and move them out of spam.

## What Is Email Warmup?

**In short:** Mailbox providers trust a sender based on history, and a new domain or mailbox has none.

Sending hundreds of cold emails from it on day one looks like a spammer who just registered a domain. Google's guidance for any sender: start with low volume to engaged recipients, increase slowly and avoid sudden spikes if you have no history of large volumes.

Mailbox warmup tools automate that. Your mailbox sends to a network of participating inboxes, and they open the messages, reply and move any that landed in spam to the inbox. Over a few weeks the daily volume rises and the mailbox builds a record of mail people engage with. IP warming is the older cousin: a volume schedule for a new dedicated IP, which Twilio SendGrid's automated schedule, for example, spreads over 41 days.

## Email Warmup Example

Example: a team buys 3 new domains and sets up 2 mailboxes on each. Every mailbox starts with 5 warmup emails a day and adds 2 a day. After 18 days each one sends about 40 warmup emails a day, and the team starts campaigns at 20 cold emails per mailbox per day, 120 a day in total.

## Email Warmup in Practice

Warmup builds a baseline. It does not fix a bad list or spammy copy. Keep warmup running at a low level during campaigns, cap cold sends per mailbox per day and spread volume across several mailboxes instead of pushing one hard.

## FAQ

### What is email warmup?

Building a new mailbox's or domain's reputation by sending low volume first and raising it over a few weeks, usually with automated messages that get opened, answered and rescued from spam.

### How long does email warmup take?

Mailbox providers don't publish a number. Ken's view: warm a new mailbox for at least two weeks before cold sending, and keep warmup running at a low level after campaigns start.

### Is email warmup necessary?

For a new domain or mailbox used for cold email, yes. Google tells senders without a history of large volumes to start low and avoid sudden spikes. An established mailbox with years of normal mail needs less.

### What is the difference between IP warming and mailbox warmup?

IP warming is a volume schedule for a new dedicated IP: Twilio SendGrid's automated schedule raises the hourly cap step by step over 41 days, and SendGrid says to warm an IP again after more than 30 days without sending. Mailbox warmup builds engagement for a new mailbox or domain, usually on a provider's shared IPs.

### Does email warmup fix deliverability problems?

No. It builds a baseline reputation, but a bad list, high bounce rate or spam complaints will undo it. Warmup works alongside clean data, authentication and steady daily volume.

## Do this in Ken

### Do This in Ken

Delivery enrolls the Google Workspace mailboxes it provisions in warmup automatically, so a new domain starts building a sending history as soon as it exists.

- Link: [Do This in Ken](/features#email-delivery)

## Related

- [GTM Glossary](/glossary): Every GTM term, grouped by topic.
- [Sender reputation](/glossary/sender-reputation)
- [IP reputation](/glossary/ip-reputation)
- [Cold email](/glossary/cold-email)
- [SPF (Sender Policy Framework)](/glossary/spf)
- [Google Postmaster Tools](/glossary/google-postmaster-tools)
- [Ken](/features#email-delivery)

## Sources

| Source | URL | Checked |
| --- | --- | --- |
| Google: Email sender guidelines | https://support.google.com/a/answer/81126 | 2026-10-17 |
| Twilio SendGrid Docs: Warm up an IP address | https://www.twilio.com/docs/sendgrid/concepts/reputation/warm-up-ip-addresses | 2026-10-17 |

## Changelog

- 2026-10-17: Page published.