Title: What Is Inbox Warmup? Email Warmup Explained | Keres AI
URL: https://www.keresai.com/glossary/inbox-warmup
Updated: 2026-10-12
Description: Inbox warmup gradually builds a new email account’s sending reputation by ramping volume and engagement, so your outbound lands in the inbox instead of spam.
Source: https://www.keresai.com/glossary/inbox-warmup (HTML). This is a Markdown copy of the page's main content for AI agents and LLM tools.

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# What is Inbox Warmup?

Inbox warmup is the process of gradually building a new email account’s or domain’s sending reputation before running outbound at scale. It starts with low daily volume and steadily increases it while generating positive engagement (opens and replies), signaling to mailbox providers that you’re a legitimate sender — so your [cold email](https://www.keresai.com/glossary/cold-email-outreach) reaches the inbox.

## Why is warmup essential?

A brand-new inbox that suddenly sends hundreds of emails looks like spam and gets filtered. Warmup builds trust slowly over days and weeks. Combined with [SPF](https://www.keresai.com/glossary/spf), [DKIM](https://www.keresai.com/glossary/dkim), and [DMARC](https://www.keresai.com/glossary/dmarc), it’s the foundation of [deliverability](https://www.keresai.com/glossary/email-deliverability). Once warmup is done, test a real message with the [spam score checker](https://www.keresai.com/tools/spam-score-checker) before raising volume.

See deliverability tools

### Want to see Inbox Warmup working in practice?

See how Keres puts it to work for your vertical and workflow.

### [Email Deliverability](https://www.keresai.com/glossary/email-deliverability)

Email deliverability is the measure of whether your emails actually reach recipients’ primary inboxes rather than the sp…

### [SPF (Sender Policy Framework)](https://www.keresai.com/glossary/spf)

SPF (Sender Policy Framework) is a DNS record that specifies which mail servers are authorized to send email on behalf o…

### [DKIM (DomainKeys Identified Mail)](https://www.keresai.com/glossary/dkim)

DKIM (DomainKeys Identified Mail) is an email-authentication method that adds a cryptographic signature to every message…

### [DMARC](https://www.keresai.com/glossary/dmarc)

DMARC (Domain-based Message Authentication, Reporting & Conformance) is a DNS policy that builds on SPF and DKIM. It tel…

### [Spam Score & Sender Reputation](https://www.keresai.com/glossary/spam-score)

A spam score estimates how likely a message or sender is to be filtered as spam, based on factors like sender reputation…

[← Back to the full glossary](https://www.keresai.com/glossary)

## Inbox Warmup — FAQ

### How long does inbox warmup take?

Typically two to four weeks to reach safe sending volume, depending on your target volume and how the domain responds — rushing it risks reputation damage.

Last updated October 12, 2026 · [Reviewed by the Keres AI team](https://www.keresai.com/editorial-policy)