How long does warm-up take?

For a target of a few thousand emails a day, plan on four to six weeks. Very large senders warm for two to three months. There's no shortcut that doesn't risk starting over — a domain throttled for ramping too fast warms slower the second time.

Do I need to warm up a new subdomain if my root domain has good reputation?

Partially. Providers weigh the subdomain's own history most, but the organizational domain contributes. A subdomain of a well-established domain warms noticeably faster than a fresh domain — still ramp it, just expect fewer weeks.

Does warming an IP differ from warming a domain?

Same idea, different ledger. On shared IPs (most ESPs) the pool's IP reputation is managed for you and your domain reputation is what you're building. On a dedicated IP you're warming both at once, which is why ESPs only recommend dedicated IPs above roughly 100k emails/month of steady volume.

What if I already sent a big blast from the cold domain and it went to spam?

Stop bulk sends, fix authentication if any of it was unaligned, and restart the ramp from week one with your most engaged recipients. Reputation recovers the same way it's built — small, clean, consistent volume — typically within a few weeks if the damage was one campaign.

How to warm up an email domain (without getting throttled)

Mailbox providers score every sending domain on history: how much it sends, how consistently, and how recipients react. A brand-new domain has no history, so Gmail and Microsoft treat sudden volume from it as a spam signature — deferrals like Gmail's 421 4.7.0 or straight-to-spam placement. Warming up means building that history deliberately before you need full volume.

Updated July 25, 2026

Before the first send: authentication is non-negotiable

Warm-up builds reputation on your domain — but only authenticated mail credits it. Sending unauthenticated mail during warm-up is worse than useless: it accrues the wrong kind of history. Before day one, publish SPF, enable DKIM, and set up DMARC at p=none so you can watch alignment from the start. Confirm with the email health check.

A week-by-week ramp that works

The principle: start tiny, send to people who will open and reply, and roughly double volume only while metrics stay clean. Numbers below are a starting shape for a cold-start domain, not a law — if bounces or spam placement appear, hold the level or step back one week.

Week	Daily volume	Who to send to
1	10–50	Colleagues, existing contacts, people who reply — real conversations, not blasts
2	50–150	Your most engaged known recipients; newest signups who expect you
3	150–500	Broader engaged segments; keep every send opt-in
4	500–1,500	Regular sends to engaged segments; start including the long tail
5+	Double weekly while clean	Full list — but keep suppressing the unengaged

Scale the shape, not the exact numbers, to your target volume. Larger targets need more weeks, not bigger jumps.

What builds reputation fastest

Replies and forwards — the strongest positive signal there is. Early sends that invite a response are worth more than any newsletter.
Opens from real, consistent recipients. Send to people who actually want the mail; every spam-report or ignore is amplified at low volume.
Clean bounce handling: remove hard bounces immediately. A 2% bounce rate that's fine at scale looks terrible across your first hundred sends.
Separate streams early: marketing on a subdomain (e.g. news.yourdomain.com) so a campaign mistake never taxes your transactional reputation.

Automated warm-up networks: read the fine print

Warm-up services that exchange fake engagement between member inboxes (auto-opens, auto-replies, rescuing mail from spam folders) violate Google's program policies, and Google has been increasingly explicit that this traffic is detectable and discountable. Some major ESPs have shut down their built-in warm-up features for the same reason. Real engagement ramped patiently is slower and safer — and the reputation it builds is the kind that survives.

How to know it's working

DMARC aggregate reports show growing volume with passing, aligned authentication — how to read them.
Google Postmaster Tools (free) starts showing domain reputation once volume justifies it — aim for it to read 'medium' or better before scaling hard.
Deferrals (4xx responses) trend to zero; a spike means you ramped too fast — hold volume until they clear.
Run the inbox test weekly during warm-up to catch placement changes early.

Sources and further reading

Google — Email sender guidelines