Warming a new sending domain without burning it
A new domain has no reputation, and mailbox providers treat no reputation as a risk. A week-by-week warm-up plan, the numbers to watch, and the mistakes that undo a month of work in a day.
A domain registered last week has no sending history. To Gmail and Microsoft that is not neutral — it looks exactly like a domain set up to spam and abandon. Warming is the process of building a record that says otherwise.
Before the first email
Authentication is not part of warm-up; it is the precondition. Before anything is sent:
- SPF lists every service that sends as the domain, and nothing else.
- DKIM signs every message, with a key of at least 2048 bits.
- DMARC is published, starting at
p=nonewith reporting turned on, so you can see what is being sent in your name.
A four-week schedule
| Week | Daily sends per mailbox | Audience |
|---|---|---|
| 1 | 5–10 | Colleagues and friendly contacts who will reply |
| 2 | 15–25 | Warm prospects and recent conversations |
| 3 | 25–40 | Best-fit cold prospects |
| 4 | 40–50 | Normal cadence, still capped |
The numbers matter less than the shape: slow, steady growth with real replies along the way. A domain that sends 200 emails on day three has told every provider what it is for.
What to watch every day
- Bounce rate. Above 2% means the list is the problem, not the domain. Verify before sending more.
- Spam complaints. Google's threshold is 0.3%, and you want to sit well below 0.1%.
- Replies. The single strongest positive signal. A thread with a reply tells the provider a person wanted this email.
The mistakes that undo a month
- Importing an unverified list in week three because the warm-up "is going well".
- Adding a link shortener or a tracking domain that other senders have already burned.
- Sending the same template to everyone, which pattern-matching filters catch quickly.
When warm-up is done
There is no finish line. A warmed domain that suddenly doubles its volume or changes its content looks like a compromised one. Keep growth gradual, keep lists clean, and treat the daily numbers as a dashboard you never stop reading.