Domain warm-up
Mailbox providers watch how much mail a domain sends — and whether recipients engage with it. A fresh domain that suddenly sends thousands of emails looks suspicious. Warming up means starting low and ramping gradually so providers can build trust in your domain before you hit full volume.
Why new domains need warming up
Every sending domain starts with zero reputation. Mailbox providers (Gmail, Outlook, Yahoo) use a domain’s historical sending pattern to decide whether incoming mail should go to the inbox, the spam folder, or be rejected outright.
A domain that goes from zero to 10,000 emails on day one triggers spam filters — not because the content is bad, but because the behaviour matches what bulk spammers do. Warming up builds a track record: consistent volume, good engagement (opens, clicks, no spam reports), and low bounces.
What mailbox providers look for:
- Steady volume growth rather than sudden spikes
- High open and click rates (engaged recipients)
- Low bounce rate (clean list)
- Low complaint rate (wanted mail)
Suggested ramp schedule
This is a starting point — adjust based on your bounce and complaint rates as you go.
| Week | Daily volume (approximate) | Notes |
|---|---|---|
| 1 | 200–500 | Send to your most engaged recipients first — people who signed up recently and have interacted with you. |
| 2 | 500–2,000 | Gradually expand to the broader list. Keep bounce rate below 3%. |
| 3 | 2,000–5,000 | Continue if metrics are healthy. Pause and investigate if complaint rate exceeds 0.1%. |
| 4 | 5,000–15,000 | By week 4 with clean metrics, most providers will have established a positive reputation for your domain. |
| 5+ | Scale to your full volume | Monitor weekly. Any sudden spike — even on a warmed domain — can reset trust. |
Transactional vs marketing. Transactional emails (receipts, OTPs, password resets) sent in response to user actions have naturally high engagement and warm a domain faster. Marketing campaigns need extra care — only send to recipients who explicitly opted in, and start with your most engaged segment.
What to send during warm-up
Do:
- Start with recipients who recently signed up or made a purchase — the highest-engagement segment.
- Send content they expect and asked for. Unexpected emails drive spam reports.
- Keep sending frequency consistent. Irregular bursts hurt more than steady daily sends.
Don’t:
- Blast your entire list from day one.
- Re-engage cold or inactive addresses during warm-up — they drive bounces and complaints.
- Import a purchased list. Bought addresses have high bounce rates, and many are spam traps.
Monitor with the health dashboard
Brixus365 tracks your sending health automatically. Check Connect → Analytics (for transactional email) or Spark → Reports (for campaigns) to see your current bounce and complaint rates.
The stat cards highlight thresholds:
| Metric | Healthy | Investigate | At risk |
|---|---|---|---|
| Bounce rate | Below 2% | Above 3% | Above 6% |
| Complaint rate | Below 0.05% | Above 0.1% | Above 0.3% |
If either metric enters the investigate range during warm-up, stop increasing volume and let it stabilise before resuming the ramp.
Warning signs and what to do
Bounce rate rising above 3%
Your list has stale or invalid addresses. Actions:
- Filter by Status → Bounced in Recipients to see which addresses failed.
- Check your list-collection form for typos (consider a double opt-in).
- Remove addresses that have never engaged across multiple sends.
Complaint rate rising above 0.1%
Recipients are marking your mail as spam. Actions:
- Check the content and subject line of the specific campaign that spiked.
- Verify you have a working unsubscribe link and honour requests promptly.
- Review your list-collection flow — were these recipients expecting this email?
Mail landing in spam folders
This is a deliverability signal, not a Brixus365 error. Actions:
- Confirm your domain has valid SPF, DKIM, and DMARC records. See Verify your sending domain.
- Reduce volume and let engagement metrics recover before scaling again.
- Send a re-permission campaign to confirm recipients still want to hear from you.
Use a subdomain for marketing. Separating transactional email (receipts, OTPs) from marketing campaigns onto different subdomains (e.g. mail.yourcompany.com vs news.yourcompany.com) protects your transactional reputation if a campaign underperforms. Verify both domains in Brixus365 settings.
What’s next
| You want to… | Go to |
|---|---|
| Add and verify a sending domain | Verify your sending domain |
| Understand bounce and complaint suppression | Bounce and complaint handling |
| Monitor transactional email health | Send History & analytics |
| Read campaign performance results | Campaign analytics |
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