How to warm up a new sending domain or IP
Mailbox providers don't trust unknown senders. Warming up means building volume gradually so they learn you are legitimate.
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A brand-new sending domain or IP address has no history. Mailbox providers have no idea whether you are a careful newsletter or a spammer, so they are cautious. Warming up is the process of earning trust by sending in small, increasing amounts to people who want your mail.
Why you can't skip it
If you send 200,000 emails on day one from a domain that was registered last week, you look like a spammer. Providers respond by sending you to spam or rejecting you outright, and a bad first impression is slow to repair.
The principles
- Start small. A few hundred emails a day is typical for a first week.
- Increase gradually. Raise volume in steps, for example by 30 to 50 percent every day or two, if the numbers stay healthy.
- Send to your most engaged people first. Recent openers and clickers. Their opens and replies tell providers your mail is wanted.
- Keep it consistent. Regular sending builds a pattern. Long gaps reset it.
- Watch the numbers at each step. If bounces or complaints climb, slow down.
There is no universal schedule. Your email platform may publish a recommended one, and shared IPs from a reputable provider often need little warming because they already carry a reputation.
Do the groundwork first
Before the first send:
- Set up SPF, DKIM and DMARC.
- Use a consistent From name and address.
- Make sure the unsubscribe link works.
Verify the list before you warm up
Warm-up volumes are small, so every bad address counts for more. A hard bounce rate of even a few percent on 500 emails is a poor start, and it is hard to recover from. Clean the list first (how-to) and begin with the people who have clicked recently.
Signs it's going well
- Low hard bounce rate
- Good open and click rates from your engaged segment
- Almost no spam complaints
- Mail landing in the inbox when you test with seed addresses
And if it goes badly
Pause. Lower the volume, go back to your most engaged segment, find the cause (usually a stale list or a missing authentication record) and resume more slowly. Pushing on makes it worse.
