Email Warmup
Email warmup is the practice of gradually increasing how much email a new mailbox or domain sends, so mailbox providers can build a sending reputation for it before larger campaigns begin.
Also called: email warm-up, inbox warmup, domain warmup
Why it matters
A brand new domain or mailbox has no sending history, and a sudden burst of messages from it can look like spam behavior to mailbox providers. Warming up means starting at a low volume and raising it step by step while watching bounces, spam complaints and replies. Teams usually do this after setting up SPF, DKIM and DMARC on the domain.
Warmup can be manual, by sending real conversations to known contacts, or automated, through warmup tools that exchange messages among a network of inboxes and mark them as important. Warmup prepares reputation but cannot fix poor targeting: a warmed mailbox that sends to unverified lists or irrelevant prospects still loses reputation. It is one part of email deliverability, not a substitute for it.
Example
A company buys two new domains for outbound and creates three mailboxes on each. At first, each mailbox sends a small number of messages to colleagues and partners who reply, and an automated warmup tool adds more exchanges. The team raises volume gradually, checks that messages are landing in inboxes, and only then adds the mailboxes to its cold email sequences.
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