---
title: "Why do emails from my new domain go to spam, and how do I warm it up?"
slug: new-domain-emails-going-to-spam
description: "Why inbox providers hold back mail from a brand-new domain, how long it lasts, and how to warm one up at any volume."
created_at: "2026-10-08"
updated_at: "2026-10-08"
humans: ["jp-valery"]
featured: true
---

Many senders are surprised that sending from a new domain brings its own challenges. As soon as you start sending at scale, inbox providers like Gmail and Microsoft slow down your mail until they've determined you're sending email people want to receive.

Whenever you're sending from a new domain, or one that hasn't sent much email, it's important to follow a few key practices, and it starts with understanding how inbox providers judge your mail.

Generally speaking, start sending at a low volume to people who expect your email, then increase it gradually as you build engagement.

## Why a new domain lands in spam

Inbox providers decide where mail goes based on the sending domain's track record. They watch how recipients react: opens, replies, "Not spam" clicks, complaints, and bounces.

A brand-new domain has no track record. Spammers often register new domains and start sending right away, so filters treat unknown domains with caution and send more of their mail to spam until they build a history.

Authentication is important. [Gmail, Yahoo](/blog/gmail-and-yahoo-bulk-sending-requirements-for-2024), and [Microsoft](/blog/microsoft-bulk-sending-requirements-2025) require SPF, DKIM, and DMARC from bulk senders. But it doesn't address the key problem: it proves the mail comes from you, not that recipients want it. Inbox providers want to see a history of sending email people want, and a new domain doesn't have that history yet.

This is temporary. Placement improves as positive signals build up.

## How long until a new domain reaches the inbox

There's no exact timeline. Some domains reach the inbox in a few days. Most get there within a week or so when they follow the practices below.

[Microsoft](/docs/knowledge-base/how-do-i-avoid-outlooks-spam-folder) (Outlook and Hotmail) and [iCloud](/docs/knowledge-base/how-do-i-avoid-icloud-spam-folder) often take longer than Gmail to trust a new domain.

<Table
  data={{
    headers: ["Speeds it up", "Slows it down"],
    rows: [
      ["Mail people expect, such as signups and login codes", "Announcements to people who never asked for them"],
      ["Steady daily volume", "Bursts, then days of silence"],
      ['Recipients opening, replying, and clicking "Not spam"', "Spam complaints"],
      ["Recent, opted-in addresses", "Old, bought, or scraped lists that bounce"],
    ],
  }}
/>

## How many emails a new domain can send per day

There's no universal limit. Each provider sets its own thresholds and adjusts them based on your sending history.

As a reference, Resend's [warm-up guide](/docs/knowledge-base/warming-up) starts a new domain at up to 150 emails on day 1 and up to 2,000 by day 7. Our [calculator](/docs/knowledge-base/warming-up#warm-up-calculator) builds a day-by-day schedule for your target volume, on any provider.

- **Start early.** Verify the domain and send real mail weeks before you need full volume.
- **Start small.** Your first days set the baseline providers compare you to.
- **Ramp gradually.** Small daily increases are safer than big jumps. If bounces or complaints rise, hold your volume until they settle.
- **Spread sends across the day.** 500 emails over 10 hours looks steadier than 500 in one minute.

## How to warm up when users trigger your volume

Password resets and login codes can't wait for a schedule. You can still shape the rest:

- **Hold back non-critical mail.** Turn on digests, reminders, and product updates gradually only after your core transactional mail is flowing.
- **Launch in waves.** Invite users in batches or through a waitlist, so signup volume grows instead of spiking.
- **Start before launch.** Send from the domain in staging to your team's own addresses at Gmail, Outlook, Yahoo, and iCloud.

Domains that send transactional mail only still need a warm-up. Expected mail builds reputation fast, but one burst, such as a launch day or a bot hammering your signup form, can still impact your trust with inboxes.

## How to build sender reputation with only a few emails a day

Each message carries more weight, so get the strongest signal you can from each one.

- **Ask recipients to check spam.** On your signup screen, mention the email might land in spam. Ask people to mark it "Not spam" and add your address to their contacts. Those are the strongest signals a recipient can send.
- **Send your most-wanted mail first.** Login codes and replies to people who wrote in get opened.
- **Keep it steady.** A few emails every day beats a week of nothing followed by a batch.

You might expect to track this in a reputation dashboard like [Google Postmaster Tools](https://support.google.com/mail/answer/9981691), which shows how Gmail rates your domain. At low volume it won't help yet: Google only shows data on days when you send enough mail to Gmail. Until then, watch your bounces, complaints, and test emails to your own inboxes.

## How to warm up a new subdomain when the root domain has a reputation

Providers track subdomains separately, but they also look at the root domain. A new subdomain like `notifications.example.com` on an established `example.com` starts with more trust than a brand-new domain.

Subdomains still need a warm-up, albeit a shorter one. Start with the mail people expect most and ramp up from there.

## What to do when Gmail throttles you mid-warm-up

Throttling shows up as a temporary deferral, not a bounce. Gmail's response looks like this:

```text
421 4.7.28 Gmail has detected an unusual rate of unsolicited email originating from your SPF domain example.com. To protect our users from spam, email sent from your domain has been temporarily rate limited.
```

It means you're sending faster than your history supports. Sending services retry deferred mail automatically, but messages expire if the deferral lasts too long.

1. Lower your daily volume to the last level that delivered cleanly.
2. Hold it there for a few days.
3. Resume ramping in smaller steps.
4. Re-send anything that expired.

Don't move the traffic to another domain to get around it, as that behavior can be flagged by inboxes and won't ultimately fix the problem.

## How to know when your warm-up is finished

Your warm-up is done when all of these are true:

- You're sending your target volume on your normal schedule.
- Inboxes are no longer deferring your emails.
- Bounces and complaints stay low and stable (0.1% is a good target).
- Test emails to your own Gmail, Outlook, Yahoo, and iCloud addresses land in the inbox.

Once the domain is warmed up, you don't need to repeat the warm-up as long as your volume stays steady. A big jump, such as 5 times your usual volume for Black Friday, needs a short ramp of its own.

## How to restart a domain that has been quiet for months

Reputation fades when a domain stops sending. After a few months of silence, restart sending in small amounts and ramp up sending as with a new domain.

- Start with recipients who engaged most recently.
- Leave out addresses that haven't opened or clicked in months. They're the most likely to bounce or turn out to be spam traps. See [audience hygiene](/docs/knowledge-base/audience-hygiene) for how to clean a list.

## Warm-up services and other shortcuts

When warming up a domain, avoid shortcuts to the natural process described above. They promise to skip the wait, but most of them hurt your reputation.

<Table
  data={{
    headers: ["Shortcut", "Verdict"],
    rows: [
      ["Automated warm-up services", "Avoid. They fake engagement between inboxes they control, and providers detect the pattern."],
      ["Emailing your own addresses", "Fine as a test across providers. The volume is too small to warm a domain on its own."],
      ["Rotating domains or top-level domains", "Avoid. Spreading volume thin across many domains is snowshoeing, a classic spam tactic."],
      ["Spreading mail across more IPs", "Doesn't help. Providers weigh domain reputation more than IP reputation."],
    ],
  }}
/>

Warm-up services also carry a lasting risk. Validity's Heatwave blocklist flags domains warmed with synthetic engagement, and that listing is permanent. [Read more on warm-up services](/blog/avoid-warmup-services).

## Warm-up checklist

1. Send from a subdomain, one per type of mail, such as `notifications.example.com` and `updates.example.com`.
2. Set up SPF, DKIM, and DMARC before your first send.
3. Verify the domain and start sending real mail weeks before launch.
4. Start with the mail people expect most: signups, login codes, and replies.
5. Increase volume gradually, and keep it steady across the day.
6. Send only to people who opted in recently. No bought or old lists.
7. Ask early recipients to mark your mail "Not spam" and add you to their contacts.
8. Keep spam complaints under 0.1%.
9. Slow down when you see deferrals.
10. Skip warm-up services and domain rotation.

## Other details to keep in mind

Consistency and positive signals matter more than following a schedule to the letter. A warm-up table built for 50,000 emails a day won't fit a domain that sends 20.

Transactional mail mostly warms itself, because every message is expected. The risk is one burst. Get the domain live a few weeks before launch with real, low-volume traffic from your team and beta users.

If marketing launches at the same time, give it its own subdomain. That way, a spike there can't throttle your login codes.

## How to warm up your domain with Resend

<Callout type="info">

- Add a [subdomain](/docs/knowledge-base/is-it-better-to-send-emails-from-a-subdomain-or-the-root-domain) for each type of mail, such as `notifications.example.com` and `updates.example.com`, so early mistakes never touch your root domain. The free tier includes 3 domains.
- Build your ramp with the [warm-up calculator](/docs/knowledge-base/warming-up#warm-up-calculator).
- Check each email's [event timeline](/docs/dashboard/emails/manage-emails). A Delivery Delayed event means the receiver temporarily deferred the message. Throttling is one possible cause, along with others such as a full inbox or a receiving server issue.
- Track bounce and complaint rates on the [Metrics page](/metrics) or by capturing these events [with webhooks](/webhooks). Keep bounces under 4% and complaints under 0.08% to stay within Resend's [account limits](/docs/knowledge-base/account-quotas-and-limits).
- Run [Deliverability Insights](/docs/dashboard/emails/deliverability-insights) on an email to check it against best practices.

</Callout>

## FAQ

**Does changing my From name or sender address hurt deliverability?**

The From name has no impact, but changing the address can affect deliverability. Keep one address per type of mail, as Google's sender guidelines ask. Avoid `no-reply@` and use an address someone reads, since replies are a positive signal.

**Can I send email from a domain that has no website?**

You can, but it's a missed signal. A website that loads on your domain helps providers and recipients trust your mail.

**Does WHOIS privacy hurt deliverability?**

No, hiding your registration details with WHOIS privacy has no effect on where your email lands.

**Do I need to warm up a domain that only sends transactional email?**

Yes. Transactional mail builds reputation fast because people expect it, but a sudden burst can still get you throttled. The [warm-up guide](/docs/knowledge-base/warming-up) covers it.

**Why doesn't Google Postmaster Tools show data for my new domain?**

Google hides Postmaster Tools data on days when your Gmail volume is too low. It fills in as your volume grows.

## Sources

- Google, [Email sender guidelines](https://support.google.com/a/answer/81126), accessed October 8, 2026
- Google, [Gmail SMTP errors and codes](https://knowledge.workspace.google.com/admin/support/troubleshooting/gmail-smtp-errors-and-codes), accessed October 8, 2026
- Google, [Set up Postmaster Tools](https://support.google.com/mail/answer/9981691), accessed October 8, 2026
- Spamhaus, [Announcing the Spamhaus CSS](https://www.spamhaus.org/resource-hub/email-security/announcing-the-spamhaus-css/) (2009), accessed October 8, 2026
- Validity, [Heatwave domain blocklist](https://lookup.validity.tools/), accessed October 8, 2026
- Resend, [Domain and IP warm-up guide](/docs/knowledge-base/warming-up), accessed October 8, 2026