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 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, DKIM, and DMARC, it’s the foundation of deliverability. Once warmup is done, test a real message with the spam score checker before raising volume.
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Email Deliverability
Email deliverability is the measure of whether your emails actually reach recipients’ primary inboxes rather than the sp…
SPF (Sender Policy Framework)
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)
DKIM (DomainKeys Identified Mail) is an email-authentication method that adds a cryptographic signature to every message…
DMARC
DMARC (Domain-based Message Authentication, Reporting & Conformance) is a DNS policy that builds on SPF and DKIM. It tel…
Spam Score & Sender Reputation
A spam score estimates how likely a message or sender is to be filtered as spam, based on factors like sender reputation…
Questions
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.
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Let Keres warm your inboxesLast updated · Reviewed by the Keres AI team