How to warm up a new sending domain
A fresh domain has no reputation, and sending as though it does is the fastest way to get filtered. A four-week schedule that works.
A new domain has no history. To a mailbox provider, "no history" and "suspicious" are close to the same thing — most domains that suddenly send large volumes are compromised or disposable.
Warming up means building a track record before you need it.
Before you send anything
Get authentication right first. SPF, DKIM and DMARC must all pass on day one — warming an unauthenticated domain builds no reputation at all.
Then pick your most engaged recipients. Warming works because positive signals accumulate, and those come from people who open, click and reply. Your own team, active customers, recent signups.
A four-week schedule
Roughly double daily, and stop if metrics slip.
Week 1 — 50 a day, rising to 500. Only your most engaged contacts. Week 2 — 1,000 to 5,000. Still engaged recipients only. Week 3 — 10,000 to 25,000. Begin including less active contacts. Week 4 — 50,000 and above. Full list, if the numbers hold.
The numbers matter less than the shape: gradual, consistent, never a step change.
What to watch, daily
- Bounce rate — must stay under 2%. Above 5% means your list is the problem, not your volume.
- Complaint rate — must stay under 0.1%.
- Open rate — falling opens usually mean spam-folder placement before any bounce appears.
If any of these move the wrong way, hold at the current volume until they recover. Do not push through.
Consistency beats volume
Sending 5,000 a day every day builds reputation faster than 35,000 once a week. Providers are modelling a pattern; an erratic one is harder to trust.
This is also why a domain that goes quiet for months and then sends heavily gets filtered. Reputation decays.
Shared or dedicated IPs
Most senders should stay on a well-managed shared pool. Your reputation rides on the pool's aggregate behaviour, which for a good provider is better than a new sender could build alone.
A dedicated IP only makes sense above roughly 500,000 emails a month, because an IP has to stay warm. Below that volume you cannot send enough to maintain it, and a cold dedicated IP performs worse than a warm shared one.
When something goes wrong
Stop. Do not push through poor numbers — reputation damage compounds, and recovery takes far longer than the pause would have.
Drop back to the last volume where metrics were healthy, hold for several days, then resume more slowly. If complaints caused it, audit what you sent and who received it before sending anything else.