How to warm up a new sending domain
Warm up a new sending domain by starting with a small daily volume and raising it only after days when bounces and complaints stayed low. Mailbox providers judge a domain partly on its history, and a new domain has none, so a full-list send on day one looks like the start of a spam run.
Why a new domain needs warming up
Every mailbox provider keeps a running opinion of the domains that send to it: how much mail arrives, how often it bounces, how many people mark it as spam, how many read and keep it. A domain that has sent nothing has no opinion attached, and an unknown domain that suddenly sends tens of thousands of messages matches the pattern of a freshly registered spam domain closely.
Warming up means giving providers a small, clean sample first, then a larger one, so the opinion they form is based on good evidence. It applies to a brand new domain and to an old one that has never sent bulk mail. It also applies after a long silence: a domain that has not sent for months has very little recent history to stand on.
What a sensible ramp looks like
- Start small and grow in steps. Tens of messages a day at first, then hundreds, then thousands, rather than one jump.
- Send to your most engaged people first. Recent customers and people who clicked or replied lately are the least likely to bounce or complain, which makes the early days count.
- Move up on results, not on dates. A calendar schedule climbs whether or not the last step went well. Watch bounces and complaints, and hold the step when either rises.
- Keep complaints very low. Gmail asks senders to keep the spam rate it reports below 0.1% and never let it reach 0.3%.
- Do not leave it idle. Steady sending builds history. A domain set up and then left untouched for a month has not warmed at all.
If something goes wrong partway through, such as a run of bounces from an old segment, do not push on. Stay at the current volume, remove the addresses that bounced, and let a few clean days pass before sending more.
How Email Digit warms a domain
You do not have to run the schedule by hand. Campaign sends from a new domain start with a daily ceiling of 50 emails and climb one step for every healthy day of sending behind them:
| Healthy sending days behind it | Daily ceiling |
|---|---|
| 0 | 50 |
| 1 | 100 |
| 2 | 500 |
| 3 | 1,000 |
| 4 | 5,000 |
| 5 | 10,000 |
| 6 | 25,000 |
| 7 | 50,000 |
| 8 or more | No warm-up ceiling |
A day counts as healthy only when:
- bounces were 5% of that day’s sends or less, and
- spam complaints were 0.1% or less.
A bad day does not move you up. Days with fewer than 20 sends are too small to judge fairly, so they count as long as something was sent; one bounce out of three messages says nothing about a domain. Today never counts until it is over, and days run on UTC.
The age that matters comes from real sends, not from when you added the domain. Only the last 120 days of sending are read, so a domain that goes quiet for months gradually loses the days it earned and starts lower when it comes back.
When a campaign is bigger than today’s ceiling
The recipients over the ceiling are held back from that send rather than pushed through it. The composer’s recipient breakdown shows a line for “Held back by domain warm-up” with the count, next to the lines for suppressed addresses and the weekly frequency cap, so you see the number before you press send. If it is large, send to your most engaged segment first and the rest on a later day, once the ceiling has climbed.
Two details make that number trustworthy:
- It is applied last. Suppressions and the frequency cap are taken out first, so the day’s allowance is spent on people who were going to receive the email anyway.
- The same people are held back in the estimate and in the send. Recipients are put in a fixed order before the ceiling is applied, so the preview and the real send agree about who goes today.
The account’s daily sending allowance
On top of the domain warm-up, every new Email Digit account has a daily sending allowance. It counts all the account’s email together: campaigns, automations, sequences and the email your app sends. Like the warm-up, it rises on evidence, never on time alone:
| Stage | Recipients a day | Rises when |
|---|---|---|
| New | 200 | you verify a sending domain and 100 messages send cleanly |
| Second | 1,000 | 1,000 messages have sent cleanly over at least 3 days |
| Third | 5,000 | you ask, and we review your sending and move you to your plan’s limit |
“Cleanly” means spam complaints under 0.1% and hard bounces under 2% of what the account sent in the last 30 days. The allowance resets at midnight UTC. When a campaign is bigger than what is left of it, the pre-send check says so, the send button tells you how many go now, and the rest of the campaign is rescheduled to go out as the allowance resets. App email over the allowance waits for the reset too; it is held, not failed. The Workspace page shows today’s figure and what raises it.
Limits worth knowing
- It covers campaign sends. The warm-up ceiling is applied when a campaign’s audience is worked out.
- Several domains share one ramp. Warm-up is tracked per account. If you send from more than one domain, they climb together, which errs toward sending less.
- Other limits can be tighter. The account’s daily allowance above and your plan’s monthly email count apply as well. Whichever is tightest on a given day decides.
- Warm-up cannot fix a bad list. It limits how fast you find out. Old, bought or unconfirmed addresses will still bounce and complain, only in smaller batches.
- No one can promise the inbox. A clean ramp gives providers good evidence. What they decide is still up to them.
Warm-up only helps a domain whose authentication already passes. Before the first send, run your domain through the free domain checker to confirm SPF, DKIM and DMARC are in place.