How to warm up a new sending domain (without torching your reputation)
Here's the uncomfortable truth about a brand-new sending domain: mailbox providers don't trust it, and they shouldn't. Most fresh domains that suddenly start sending bulk email are spammers who just got their last domain blocked.
So Gmail, Outlook, and Yahoo treat you as guilty until proven innocent. Send 10,000 emails from a domain with no history and watch them get deferred, throttled, or dumped straight into spam — regardless of how good your authentication is.
The fix is warm-up: deliberately ramping your volume while showing mailbox providers that real humans want your email. Done right, it takes 4–6 weeks. Done wrong, it takes longer than that to undo.
What reputation actually attaches to
Two things carry reputation: your IP address and your domain.
If you're sending through a modern platform, you're almost certainly on shared or managed IPs that already have history — so IP warm-up is mostly handled for you. What isn't handled for you is domain reputation. That belongs to you, follows you across providers, and starts at zero the day you register the domain.
Domain reputation is also the one Gmail cares about most. You can check yours directly in Google Postmaster Tools — set it up before you send your first campaign, not after your first problem.
The ramp
The pattern is simple: start tiny, send to your most engaged people first, and roughly double volume each week as long as the metrics stay clean.
Week 1 — up to ~50/day. Send only to people who will genuinely open and reply: your team, existing customers, people who signed up this week. Replies are the strongest positive signal a mailbox provider can see.
Week 2 — up to ~100–200/day. Expand to subscribers who opened something in the last 30 days. Watch bounces and complaints daily.
Week 3 — up to ~500/day. Add the last-90-days openers. If opens hold and complaints stay near zero, keep going.
Week 4–6 — double weekly until you reach your target volume. Only now do you touch the colder parts of your list — and honestly, if someone hasn't engaged in a year, reconsider whether to mail them at all.
The exact numbers matter less than the shape: gradual, engagement-first, and responsive to feedback.
The three mistakes that reset you to zero
Importing an old list on day one. A five-year-old list is full of dead addresses and spam traps. Hard bounces on a new domain are radioactive — verify the list before it gets anywhere near your sends.
Jumping volume 10x because "things looked fine." Volume spikes are the classic spammer signature. Mailbox providers pattern-match on them instantly. Doubling is the ceiling.
Ignoring early warning signs. A deferral ("try again later") is Gmail politely telling you to slow down. If you respond by pushing more volume, the next message isn't polite.
What "clean metrics" means during warm-up
- Hard bounce rate under 2% — ideally well under 1%
- Spam complaint rate under 0.1% — 0.3% is where Google starts blocking
- Open rates stable or rising week over week
- No deferral spikes in your send logs
If any of these break, don't push through. Hold volume flat (or drop back a week) until they recover. Warm-up is the one phase of email where patience is directly convertible into deliverability.
The bottom line
Warm-up isn't a hoop to jump through — it's how mailbox providers learn who you are. Give them 4–6 weeks of small, clean, wanted email and you'll have a domain reputation that survives the occasional bad campaign. Skip it and your first impression at Gmail may be your last for a while.
PristineSend is built around exactly this: we verify your list before you send, suppress bounces and complaints automatically, and pause sending if your reputation signals go sideways — because fixing a burned domain is much harder than protecting a clean one.