How to Warm Up a New Sending Domain

Before you send anything

Confirm SPF, DKIM and DMARC are fully verified — not "pending" — before your first send. A warm-up campaign sent from an unauthenticated domain teaches providers the wrong lesson from message one.

A practical 4-week ramp

There's no universally "correct" schedule, but this shape works for most teams moving off a previous provider or launching a new product domain:

• Week 1: send only to your most engaged contacts — recent signups, active users, people who’ve opened your email before on a different domain. Cap daily volume low (a few hundred, not thousands).
• Week 2: roughly double volume, still favoring engaged segments. Watch bounce and complaint rates daily, not weekly.
• Week 3: extend to your broader active list, continuing to grow volume. Start layering in regular send types (transactional plus the occasional campaign) rather than warm-up sends alone.
• Week 4 and beyond: approach full intended volume, provided complaint rate stays under ~0.1% and bounce rate under ~2% throughout. If either spikes, pause the ramp — don’t push through it.

Prioritize engagement over volume

The single biggest lever during warm-up is who you send to, not how much you send. A smaller batch of people who reliably open and click teaches providers your mail is wanted; a larger batch that mostly goes unopened teaches them the opposite, and does it faster than you'd think.

What to do if you’re migrating, not starting fresh

If you’re moving an existing, already-warm sending relationship to a new domain (say, after a rebrand), you still need to warm up the new domain’s reputation independently — reputation doesn’t transfer between domains. Run the same ramp, but you can move faster since your list is already validated and engaged; two to three weeks is often enough rather than a full month.

Keep an eye on it after warm-up "ends"

Warm-up isn’t a one-time task with a finish line — reputation is a continuously re-evaluated signal. A sudden volume spike six months in (a big product launch email, say) can still trigger the same caution from providers that a new domain would. Ramp big jumps in volume the same way you ramped the original warm-up, even on an established domain.