What Is Domain Warmup? The Basics

Domain warmup is the practice of raising a new domain's daily send volume in small steps. Mailbox providers see steady, wanted mail before you send at full speed. It builds a sending reputation from zero.

Most guides stop at the schedule. The schedule is the easy half. The hard half is what you send to, because a clean ramp to a dirty list still ends in the spam folder.

Key takeaways

• A new domain has no reputation. Providers treat unknown senders with suspicion until you show a pattern.
• Warmup means a slow ramp, low complaints and low bounces, usually over two to six weeks.
• Authentication (SPF, DKIM, DMARC) comes first. Warmup without it is wasted time.
• Verified addresses protect the ramp. Bounces in week one do the most damage.

What it is

Domain warmup is a gradual rise in the volume you send from a new domain or mailbox, with clean engagement signals, until providers trust it at full volume.

Reputation attaches to your sending domain, and to the IPs behind it. A fresh domain has no history, so Gmail and Outlook have nothing to judge it on. Mail from an unknown domain at high volume looks like a spammer who just registered a domain.

Warmup gives providers a history. You start small, send to people who will not complain, and add volume as the signals stay clean. Our domain reputation glossary entry covers what providers score. The longer version of the ramp lives in the email domain warmup guide.

Warmup tools also exist. They send mail between a network of mailboxes to create opens and replies. Whether they help is debated, and nothing here depends on them. The basics work with or without one.

How it works

Warmup works by ramping volume while you keep spam complaints, bounces and authentication failures low. Each step needs clean results before the next one.

1. Authenticate the domain. Publish SPF, turn on DKIM, and add a DMARC record. Google requires SPF or DKIM from all senders, and all three from anyone sending 5,000 or more messages a day (Google email sender guidelines, September 2026).
2. Start with a few messages a day per mailbox. Send one-to-one mail to people who know you: colleagues, partners, customers. Replies are the strongest signal.
3. Add volume in steps. Raise the daily total every few days, not every day. Google's guidance for volume changes is to increase gradually and to watch server responses, spam rate and domain reputation as you go.
4. Gate each step. Move up only if spam complaints, bounces and delays stay flat. If any of them rise, hold the volume or step back.
5. Add cold outreach last. Bring in prospecting mail once the domain sends steadily. Keep the first prospect batches small and verified.
6. Keep sending. A domain that goes quiet for weeks loses its rhythm. Hold a steady floor of volume.

A worked example

Say you buy a new domain and set up three mailboxes. This ramp is an illustration, not a rule. Providers publish no official schedule, so treat the numbers as a starting plan and adjust to your own results.

Google asks senders to keep the spam rate reported in Postmaster Tools below 0.10% and to avoid ever reaching 0.30% (Google email sender guidelines, September 2026). Those two numbers are the only hard limits in the table.

Warmup vs list hygiene

Warmup builds trust in your domain. List hygiene decides whether you keep it. People confuse the two because both are "deliverability work", but they fix different problems.

A warm domain can still collapse on a bad list. A perfect list sent from a cold domain at 500 a day still gets throttled. You need both.

When it matters

Warmup matters most when the sending history is short or broken. These are the cases where skipping it costs you.

A brand new domain

A new domain has no history at all. Cold outreach teams register separate domains to protect the main one, and each of those needs its own warmup. Check the spelling of the domain you register against the typo domain glossary entry, so you do not send from a lookalike you did not mean to use.

A new mailbox on an old domain

A new mailbox starts without its own sending pattern. The domain's reputation helps, but a sudden jump from one mailbox to ten can still look odd. Ramp each new mailbox on a short schedule.

A big volume jump

Going from 50 sends a day to 2,000 is a volume jump even on an old domain. Google advises increasing volume gradually when your sending changes. Apply the same stepped ramp.

Coming back after a long pause

A domain that sent nothing for months is close to cold again. Restart at a lower volume than you left at, and gate the climb the same way.

How LeadOcean handles it

LeadOcean does not warm domains. It has no sequencer and no sending. What it controls is the list quality side: every person record carries an email_status, and the emailStatus filter lets you decide which addresses enter your ramp.

By default, count_leads counts mailable people: statuses verified, catch_all_valid and catch_all. For the first weeks of a warmup, filter tighter. Ask for verified only, and size the list first, because a count costs nothing.

curl -G https://api.leadocean.io/v1/people/search \
  -H "x-api-key: $LEADOCEAN_API_KEY" \
  --data-urlencode "jobLevel=VP" \
  --data-urlencode "country=US" \
  --data-urlencode "emailStatus=verified" \
  -d "count=true" -d "limit=1"

The response returns meta.total and no rows. meta.total is capped at 100,000, per the OpenAPI spec, September 2026. Remove count and limit=1 to pull rows, and each person returned counts as one record.

The email status values are verified, catch_all_valid, catch_all, risky, unknown, untested, invalid, role, disposable, spam_trap, abuse, derived and none. Keep invalid, spam_trap, abuse, disposable and risky out of any warmup batch.

LeadOcean does not refund or credit back bounced emails, so read email_status before you send. For a larger list, the Exports page in the app lets you set the same filters, pick columns and download a CSV. Free includes 1,000 records, one-off, with no card. Pro is $499 a month. See pricing.

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