Warm-up

A new sending domain starts on a small daily limit and grows from there. Gmail and Outlook do not trust a domain they have never seen, so a domain that starts small keeps its mail out of spam.

The limit

Every send from the domain counts: the API, SMTP, batches, broadcasts and automations. Broadcasts, automations and MARKETING sends can use 80% of the day. The last 20% is kept for single emails from your app, like password resets, so a broadcast cannot use them up.

The day resets at midnight UTC. A limit your account has for the whole team does not lift a domain's warm-up.

What happens at the limit

• An API or SMTP send answers 429 RATE_LIMITED with details.reason DOMAIN_WARMUP_LIMIT. Nothing was sent.
• A broadcast sends what fits and carries on the next day from where it stopped.
• An automation waits and carries on later.

See where a domain is

Open the domain in Domains. The Warming up card shows today's count, the limit and when the next step starts.

With the API, GET /v1/domains/{id} returns safeguards.warmup and Get a domain's sending status returns warmup and dailyCap, each with sentToday.

Migrating from Resend, SendGrid or Mailchimp

If you migrate with the Migration Center, Notix reads a short, recent sample of your sending at your old provider, in the background after you connect. A domain starts at 2,000 a day instead of 200 when all of this holds for that exact domain (the same name you add in Notix, not a sibling under the same root):

• it was added at your old provider at least 30 days ago, and is verified there;
• in the last 7 days it delivered at least 50 emails a day on at least 5 days;
• those emails went to at least 10 different recipient domains;
• at most 2% of the sample bounced and at most 0.05% was marked as spam.

Only real recipients count: your own domain, your team's addresses and test addresses (such as delivered@resend.dev) are left out. Anything less starts at the normal 200 a day.

Above 2,000, a person decides. On the switch-over step or the domain's Warming up card, choose Request a higher start and give the amount you want. A Notix admin looks at the domain's age at your old provider, the daily volume and bounce rate we sampled, and its DNS in Notix, then approves your amount, approves a different one, or declines. You can also ask with the API (POST /v1/domains/{id}/start-request) or the request_higher_start MCP tool.

What each provider shows:

• Resend: when the domain was added and whether it is verified, and your newest sent emails from the last 7 days, read page by page until the sample is enough. A domain sending a great deal more than 2,000 a day may not fit the sample; ask for a higher start.
• SendGrid: your authenticated domains and, with read access to stats (stats.read), the account's daily delivered, bounce and spam-report numbers for the last 7 days. SendGrid does not show who mail went to or when a domain was added, so a SendGrid domain starts at 200 and can ask for a higher start. The account's numbers are shown to the admin only when the account has exactly one domain.
• Mailchimp: your verified domains and the campaigns you actually sent in the last 7 days. A Mailchimp domain can earn the 2,000 start at most; above that, ask.

The start applies once the domain is fully verified in Notix: the domain, DKIM and MAIL FROM. You add the DNS records yourself, as for any domain. It also lifts your team's new-account daily limit, but only for email sent from that domain; mail from your other domains stays on the normal ramp.

Some starts are checked by a person first, for example when the old account does not look like yours, or when the same provider account or domain was connected by another team. The sample counts for 30 days, and only from your latest connect.

Everything else still applies: bounces and spam complaints are watched from the first send. A pause, or a hold on marketing after a sudden rise in bounces, on any of your domains ends every higher start your team has, and the team lift, for good; after a resume a domain is on the normal 7-day probation. Deleting a domain gives its start back. The domain keeps its start for its warm-up window and then has no warm-up limit, like any other domain.

The switch-over step of the migration shows each domain's start, or why it did not qualify, naming what was measured. The domain's Warming up card shows its starting step and the reason, and the API returns it as warmup.start (reason, provider, verifiedSince, startingCap). startingCap is what the domain can actually send: the lower of its start and your team's own daily limit.

Need more on day one?

Moving an existing, clean list some other way? Contact us. Notix can set a different limit for a domain while it warms up.