How to warm up a new sending domain
A new domain has no sending reputation. Warm it up by ramping volume gradually over several weeks while keeping engagement high and complaints near zero.
A new domain has no sending reputation, and mailbox providers treat unexplained volume from an unknown domain as a spam signal. Warming up means ramping volume gradually over several weeks while keeping engagement high and bounces and complaints near zero. Authenticate first, start small, target your best-fit prospects, and increase only while the metrics hold.
Who this applies to: 11x workspace Admins launching outbound on a new domain or new mailboxes. If your domain is established and mail is going to spam, read Why are my emails going to spam? instead.
Why warm-up is necessary
Mailbox providers decide where mail goes based on your sending history. A new domain has none, so every signal carries disproportionate weight. Two things follow:
- Early mistakes are expensive. A high bounce or complaint rate in week one shapes how the domain is treated for months.
- Early wins compound. Replies and positive engagement during warm-up build reputation faster than volume ever does.
Never send at target volume on day one from a new domain. This is the single most damaging deliverability mistake, and reputation repair takes weeks where prevention takes patience.
Step 1 — Authenticate before sending anything
Publish and verify SPF, DKIM, and DMARC on the new domain first. Sending unauthenticated mail from a brand-new domain combines the two worst signals available.
See Set up SPF, DKIM, and DMARC, then confirm with the domain health checker.
Step 2 — Let the Deliverability Engine pace it
The Deliverability Engine paces send volume against sending reputation automatically. Use it rather than managing the ramp by hand.
The main way teams undermine warm-up is overriding the pacing because early results look good. Good week-one results on 20 sends a day tell you nothing about 500 a day.
Step 3 — Send to your best-fit prospects first
Warm-up is the wrong time to test a speculative segment. Engagement is what builds reputation, so use the segment most likely to reply.
Pick your strongest ICP segment
The one where you have the clearest proof points and the highest historical reply rate.
Enable the Qualification Agent
So out-of-profile prospects don't consume warm-up volume or generate complaints.
Use verified contact data
Bounces are the fastest way to damage a new domain. Source from the verified database rather than uploading an unvalidated list.
Invest in the knowledge base first
Generic messages don't get replies, and replies are what you're trying to earn. See Set up Alice → build the knowledge base.
Step 4 — Ramp gradually
Increase in steps, holding at each level long enough to see whether the metrics hold.
| Phase | Focus | Increase volume only if |
|---|---|---|
| Week 1 | Very low volume, best-fit prospects only | Bounces near zero, no complaints |
| Week 2 | Small increase | Reply rate healthy, placement stable |
| Weeks 3–4 | Continued stepwise increase | All metrics holding |
| Week 5+ | Approach target volume | Sustained stability at the previous level |
These phases are a shape, not a schedule. The rule that matters is: increase only while metrics hold, and hold or reduce the moment they don't. A domain that takes eight weeks to reach target volume is a success. One that reaches it in two and gets blocklisted is not.
Step 5 — Monitor the right metrics
Check mailbox health in 11x analytics daily during warm-up.
| Metric | What you want | What it means if it slips |
|---|---|---|
| Bounce rate | Near zero | List quality problem — stop and fix the data |
| Complaint rate | Effectively zero | Targeting problem — tighten the ICP immediately |
| Reply rate | Healthy and stable | Low replies mean low engagement signal; improve relevance |
| Inbox placement | Stable or improving | Declining placement means hold volume now |
| Per-mailbox variance | Consistent across mailboxes | One bad mailbox drags the whole domain |
Watch per-mailbox figures, not just the domain aggregate. A single mailbox with a high complaint rate can pull down an otherwise healthy domain, and the aggregate hides it.
Common mistakes
When warm-up is complete
You're through warm-up when you've held target volume for a sustained period with bounces near zero, complaints effectively absent, stable inbox placement, and consistent metrics across mailboxes. There's no fixed date — it's the metrics, held.
Next steps
Set up SPF, DKIM, DMARC
Do this before you send anything.
Why emails go to spam
Diagnose an established domain.
Set up Alice
Full outbound configuration.
Help Center
All articles and tools.
Still need help
Email support@11x.ai with your sending domain, current daily volume, and your bounce, complaint, and reply rates.