Warm up a new domain
Build sending history on a new domain with a realistic volume ramp, starting with your most engaged contacts and watching the right numbers.
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A new sending domain has no history, so receiving providers have nothing to judge it on except the volume it suddenly produces. Warming up means building that history deliberately, over several weeks, before you send at full volume. When you finish this page you will have a ramp schedule you can follow and a short list of numbers to check at each stage.
Before you start
Authenticate the domain first. SPF, DKIM and DMARC should all be verified before the first message goes out, because a warm-up that sends unauthenticated mail builds the wrong history. See Authenticate your domain.
Why volume has to ramp#
Mailbox providers rate limit senders they do not recognize. A domain that has never sent anything, then sends 100,000 messages in one afternoon, matches the behavior of a domain registered specifically to send spam before being abandoned. The filtering response is immediate and it is applied to the whole send.
The same 100,000 messages, spread over five weeks with rising daily volume and good engagement throughout, tell a different story: a real business with a real schedule and real readers. The messages are identical. The pattern is what is being read.
Warming up applies whenever a domain has no recent history, which includes three cases people often miss: a domain you have owned for years but never sent marketing mail from, a new marketing subdomain on an established domain, and a domain that sent regularly until it went quiet for six months or more.
Send to your best contacts first#
The ramp is not only about volume. It is about who receives the early sends.
Positive engagement is what turns an unknown domain into a trusted one. So the first sends should go to the people most likely to open, click and reply: recent signups, active customers, anyone who opened something in the last 30 days. Sort your audience by recency of engagement and work down that order as volume increases.
This has a second benefit. If something is wrong with your setup, you find out on a small send to a forgiving audience rather than on a large send to an indifferent one.
Leave the least engaged portion of your list until last, or leave it out of the warm-up entirely and deal with it afterwards once the domain has a history to spend.
An example ramp#
The shape to aim for is a small start with roughly a doubling every few days, sending on most days rather than in weekly bursts. Consistency is part of what is being measured.
Here is a concrete five-week schedule for a sender heading toward 100,000 messages a month. Scale the numbers to your own list, keeping the shape.
| Week | Messages per sending day | Sending days | Audience |
|---|---|---|---|
| 1 | 200, then 400 | 3 to 4 | Opened or clicked in the last 30 days |
| 2 | 800, then 1,500 | 4 | Opened or clicked in the last 60 days |
| 3 | 3,000, then 6,000 | 4 to 5 | Active in the last 90 days |
| 4 | 10,000, then 18,000 | 5 | Active in the last 6 months |
| 5 | 30,000, then full volume | 5 | Full list, minus anything long dormant |
Two rules govern the table.
Never more than double in a step. If yesterday was 3,000, today is at most 6,000. Doubling every second or third day is faster than most senders need.
Do not skip forward to catch up. If you miss a few days, resume at the last volume you sent successfully rather than at the number the calendar says. The ramp is a sequence, not a timetable.
If your total list is small, say under 5,000 contacts, the ramp is shorter and simpler. Two weeks of sending to progressively larger slices, starting at a few hundred, is usually enough, because your full volume is never large enough to look like a spike.
What to check at each stage#
Before each increase, look at the last send and answer three questions.
Did it get delivered? Compare the delivered figure against what you sent. A sudden drop means a provider started rejecting or deferring you.
What is the complaint rate? This is the one that stops the ramp. Under 0.05 percent, continue. Between 0.05 and 0.1 percent, hold at the current volume for another send instead of increasing. Over 0.1 percent, stop increasing, go back to a more engaged audience, and find out which group produced the complaints.
What is the bounce rate? Over 2 percent hard bounces means the list needs cleaning before you send to more of it. Stop the ramp and run verification on the portion you have not sent to yet.
A fourth thing worth watching is whether the numbers differ sharply by mailbox provider. If one large provider shows much lower delivery or much higher deferral than the others, that is a provider-specific reputation issue rather than a list issue. Hold volume steady and let time do the work rather than pushing harder into it.
Careful
Do not run a warm-up and a large one-off announcement in the same week. The announcement will be the spike the warm-up exists to avoid.
After the ramp#
You are warmed up when you have sent at your target volume for a week without the delivery, bounce or complaint numbers moving. At that point the domain has a history, and the job changes from building reputation to not spending it.
Keep sending regularly. A domain that goes quiet for a couple of months loses the standing it built, and returning to full volume after a long gap means a short ramp again. Regular, moderate sending to people who read your mail is what keeps the history current.
Last updated September 10, 2026