Cold Email Warmup
The 4-6 week process of gradually ramping email-sending volume on a fresh inbox to build sender reputation with the major mailbox providers — a prerequisite for cold campaigns.
A brand-new inbox (martin@youragency.com) sending 100 cold emails on day 1 will land in spam at Gmail, Outlook, and Yahoo within hours. The mailbox providers grade sender reputation on a track record of legitimate sends, recipient engagement, and complaint rate. A fresh sender has none of those signals — and gets the default treatment, which is the spam folder.
Warmup mimics legitimate engagement. The inbox sends and receives email with other warmup-network inboxes for 4-6 weeks, gradually scaling daily volume from 5-10 sends to 30-50 sends. The exchanges look like normal conversation to mailbox providers; reputation accrues; by week 6 the inbox is ready for production cold campaigns at 30-50 sends per day.
Skipping warmup is the most common mistake in cold-email programs. The cost is not just deliverability on day one — it's permanent reputation damage that takes 60-90 days to repair, plus burn-out of the email domain itself.
Related terms
- Cold Outbound CadenceThe structured sequence of touches (call, email, voicemail, SMS, follow-up) an agency runs against each cold prospect — the difference between random outreach and a repeatable conversion engine.
- Reply AttributionLinking an inbound email reply back to the originating cold-outbound campaign and prospect — required for measuring per-prospect close-rate and feeding outcome tracking.
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