You warm up a new email domain by sending a small number of real, wanted emails first and raising the volume slowly over several weeks. Mail providers do not trust a domain they have never seen, so a sudden burst of messages looks like spam. There is no official schedule, only cautious practice.
Why a new domain needs warming up
Mail providers such as Gmail and Outlook keep a reputation for every sending domain. It is built from how people react to your mail: do they open it, reply, ignore it, or mark it as spam?
A new domain has no history at all. That is not neutral. Spammers register fresh domains every day, so providers treat unknown senders with care. If a domain that was registered last week suddenly sends hundreds of emails, the pattern looks like abuse, and the mail goes to spam or is refused.
Warming up means building a short, clean history before you ask for more. You show the providers three things:
- The domain is set up properly.
- Real people receive the mail and answer it.
- The volume grows steadily, without jumps.
The same idea applies when you start a newsletter from a new domain or move to a new mail provider.
Before the first email: the setup
- Buy the domain in your own name. For outreach, many senders use a second domain that is close to their main one, so a mistake does not hurt everyday business mail.
- Let it rest for a while. Many senders wait a week or two before sending anything. A domain that sends on its first day stands out.
- Put a real website on it, or forward it to your main site. A domain with no website looks disposable.
- Create mailboxes with real names at a serious provider such as Google Workspace or Microsoft 365. Use anna@ rather than sales1@. Add a photo and a signature.
- Add SPF, DKIM and DMARC. Without them, warming up is wasted effort. See SPF, DKIM and DMARC in plain words.
- Test. Send one email to a Gmail address and check under Show original that all three say PASS.
An example schedule for one mailbox
The table below is an example of common cautious practice. It is not an official limit from any provider, and it is no guarantee. Slower is always safer.
| Phase | What you send | Emails per day, per mailbox |
|---|---|---|
| Week 1 | Real conversations only: colleagues, partners, your own other addresses, suppliers. Ask them to reply. | A handful |
| Week 2 | More of the same. Sign up for a few newsletters so mail also comes in. | About 10 |
| Week 3 | First real outreach, to your best and most carefully checked contacts. | About 10 to 20 |
| Week 4 and after | Raise slowly, by a few emails per day each week. | Many senders stop at a few dozen |
Rules that matter more than the exact numbers:
- Send on working days and spread the emails over the day. Do not send them all in one minute.
- Increase in small steps. Never double from one day to the next.
- If something goes wrong, go back one step and wait.
- If you need more volume, add another mailbox and warm it up too. Do not push one mailbox harder.
What counts as a good signal
Providers watch what recipients do. During the warm-up, try to collect good reactions and avoid bad ones.
| Helps | Hurts |
|---|---|
| Replies | Spam complaints |
| The recipient moves your mail from spam to the inbox | Bounces from addresses that do not exist |
| The recipient adds you as a contact | Mail deleted unread, again and again |
| Normal back-and-forth threads | Sudden jumps in volume |
A simple first-week message to people you know:
Subject: New address
Hi [first name], I have a new email address for [company]. Could you reply with one line so I know this arrived? Thank you. [Your name]
Keep early emails plain. Short text, no attachments, at most one link, no tracking images. Verify every address before you write to it, because early bounces weigh heavily on a young domain.
About automated warm-up tools
Many sending tools offer automated warm-up. Your mailbox joins a pool of other mailboxes that send each other emails, open them and reply automatically.
Be aware of what this is. The activity is artificial. Mailbox providers do not endorse it, and they work on recognising it. Some senders use these tools anyway, others avoid them. A tool cannot replace the real thing: relevant emails to people who are glad, or at least not annoyed, to get them.
If you use one, treat it as a small addition in the first weeks, and do not rely on its score as proof that your mail reaches the inbox.
Warning signs, and what to do
- Your test emails to your own Gmail or Outlook address land in spam.
- Bounces increase.
- Replies stop completely, although the volume is the same.
- Google Postmaster Tools shows a rising spam complaint rate. Google says to stay below 0.3%.
- Your provider sends a warning or limits the mailbox.
If you see one of these: pause outreach for several days, keep only normal conversations going, check SPF, DKIM and DMARC again, clean the list, and restart at a lower volume.
Warm-up is the technical side. The legal side comes first, so check where cold email is allowed. If you want this done for you, Astranode offers a cold email setup by quote: domains and mailboxes in your name, authentication, warm-up and templates, for outreach to US and UK business addresses only.
Start with a few real conversations, grow slowly over weeks and step back at the first warning sign. A schedule is cautious practice, not a rule from the providers.