To warm up an email domain for cold email, set up its records, then have each mailbox send and receive a small, growing amount of normal email for at least two weeks before any cold email goes out. Cold volume then starts low and rises slowly.
This page covers how to do it, step by step. For how long it takes and the full day-by-day schedule, see our email warm-up guide.
How do you warm up an email domain for cold email?
You warm up a cold email domain in seven steps, and the first two happen before any warm-up mail is sent.
- Set up the domain properly. A separate sending domain, never your main one.
- Authenticate it. SPF, DKIM and DMARC all passing.
- Create the mailboxes. Usually two per domain, on Google Workspace or Microsoft 365.
- Start warm-up on every mailbox. A few emails a day at first.
- Raise the volume slowly. A little more each day for at least 14 days.
- Check where the warm-up mail lands. Inbox or spam, measured, not guessed.
- Start cold email low. A handful a day, rising over the next two weeks, with warm-up still running.
The rest of this page explains each step and the choices inside it.
Do you warm up the cold email domain or each mailbox?
You warm up each mailbox, and the domain builds its reputation from what all its mailboxes do. There is no separate switch for warming a domain.
Inbox providers like Gmail judge a sender on both the domain and the individual address. A domain with two well-warmed mailboxes has a good start. A domain where one mailbox is warmed and the other sends cold email on day one gets judged partly on the bad behavior.
That is why every mailbox on a cold email domain should follow the same warm-up and ramp. Adding a new mailbox to an existing domain later still needs its own warm-up.
What do you set up before warming up a cold email domain?
Before warming up a cold email domain, it needs to be a separate domain with SPF, DKIM and DMARC passing. Warm-up on a broken setup only measures the broken setup.
- A separate sending domain. If something goes wrong, your main business domain stays safe. Our cold email domains guide covers how to choose and buy them.
- Authentication. SPF, DKIM and DMARC records, each checked as passing. Our SPF, DKIM and DMARC guide has the exact records, and our cold email deliverability guide explains what Gmail, Yahoo and Outlook require.
- Real mailboxes on a major provider. Google Workspace or Microsoft 365 give a new domain the provider's own reputation to start from.
- A complete profile. A real name, a signature and a profile photo, as a person would have.
- A simple website on the domain, or a redirect. Someone who looks the domain up should find your business, not an empty page.
How do you run cold email warm-up step by step?
Run cold email warm-up by connecting each mailbox to a warm-up network, starting at a few emails a day and adding a few each day for at least 14 days. No cold email goes out during this period.
- Connect each mailbox to a warm-up tool. Most cold email platforms include one. The tool sends your mailbox's emails to other real mailboxes in its network and has them reply.
- Start small. We start each mailbox at 4 warm-up emails on day one.
- Add a few each day. We reach 50 a day by day 14. A mailbox that jumps from 0 to 50 looks hijacked, even if every recipient is friendly.
- Make sure replies happen. Replies are the strongest good signal a provider sees. We set warm-up replies at 45% of messages.
- Keep it running. Warm-up continues after cold email starts and never stops while the mailbox sends.
The full 14-day schedule, with the number for every day, is in our email warm-up guide.
How do you warm up a cold email domain manually?
You can warm up a cold email domain manually by emailing people you know from each new mailbox and asking them to reply, but it is slow and hard to measure. Most senders use a warm-up tool for that reason.
A manual warm-up looks like this:
- Send a few real emails a day from each new mailbox to colleagues, friends and existing contacts.
- Ask them to reply and, if a message landed in spam, to mark it "not spam".
- Send to a mix of Gmail, Outlook and company addresses, not just one provider.
- Add a few more each day, and keep it up for at least two weeks.
The hard part is volume and measurement. Two mailboxes reaching 50 warm-up emails a day each is 100 real conversations a day, and you have no inbox-versus-spam number unless every recipient tells you where the message landed.
| Manual warm-up | Warm-up tool | |
|---|---|---|
| Cost | Free | Usually included in a cold email platform |
| Daily volume | A handful of emails | Rises to dozens a day per mailbox |
| Replies | Depends on your contacts | Set automatically |
| Spam rescue | Only if recipients notice and act | Automatic |
| Measurement | Guesswork | Inbox-versus-spam rate per mailbox |
| Time from you | Every day for weeks | Setup once |
Manual warm-up suits one mailbox, a small business and no rush. For several sending domains, a tool is the only practical option.
How do you know a cold email domain is warmed up?
A cold email domain is warmed up when every mailbox has done at least 14 days of warm-up and its warm-up mail is landing in the inbox, measured on a real sample. Time alone is not enough.
This is the check behind step 6, and the rule we use, written into our code:
| Check | Ready when |
|---|---|
| Days of warm-up | 14 or more |
| Warm-up messages measured | 20 or more in the last 7 days |
| Warm-up mail landing in spam | Under 10% |
If a mailbox does not meet all three, it keeps warming. If its spam rate stays high, the problem is usually the setup, and the fix is to check authentication and the domain itself. Apollo's own guidance warns that warm-up may not repair a domain whose reputation is already damaged.
Once a mailbox passes, cold email starts at 5 a day and rises to 30 a day over 14 sending days. Pipefire runs this check and the ramp automatically on every mailbox; our warm-up feature page shows what you see while it happens.
How to warm up an email domain for cold email FAQ
What should I send when warming up a cold email domain manually?
Short, normal emails that invite a reply: a question, a quick update, a thank-you. Avoid links, attachments and anything that reads like a sales pitch, since you want replies, not just opens.
How many emails a day should I send to warm up a cold email domain?
Start with a handful per mailbox and add a few each day. We start at 4 and reach 50 warm-up emails a day by day 14, with a cap of 80 emails a day per mailbox once cold email is added.
Can I warm up an old domain for cold email?
Yes. An older domain that has never sent email still needs warm-up, because mail history matters more than age. Check that it has no record of spam from a previous owner first.
Is warming up a cold email domain different on Outlook and Gmail?
The steps are the same on Google Workspace and Microsoft 365. Make sure warm-up mail goes to both Gmail and Outlook addresses, since each provider builds its own view of your domain.
What happens if a cold email mailbox fails its warm-up readiness check?
It keeps warming, with cold email held at zero, and is checked again as new warm-up results come in. We re-read every mailbox every 6 hours. Most failures trace back to the setup, usually a missing authentication record or a domain with a spam history, so fix that rather than waiting out the clock.