Providers throttle or reject sudden volume from unknown senders. Skipping warm-up is the most common way new domains end up in spam permanently.
The metrics that matter#
- Authentication pass rate: share of mail passing SPF, DKIM, and DMARC alignment. Healthy: 99% or higher.
- Spam complaint rate: Gmail enforces at 0.3%; stay under 0.1%.
- Hard bounce rate: under 2%; above 5% triggers platform reviews.
- Inbox placement: above 90% across major providers via seed tests.
- Engagement: click and reply rates by segment; opens are unreliable after Mail Privacy Protection.
Where to read them#
- Google Postmaster Tools for Gmail domain reputation, spam rate, and authentication.
- Microsoft SNDS and JMRP for Outlook.com IP reputation and complaints.
- Your ESP's delivery and bounce reports.
- DMARC aggregate reports for authentication by source.
Improving the numbers#
- Start with 20 to 50 messages per day per mailbox to your most engaged, opt-in contacts.
- Double volume every 2 to 3 days while complaint and bounce rates stay clean.
- Prioritize recipients likely to reply or click; positive engagement accelerates trust.
- Monitor Postmaster Tools daily and pause the ramp if reputation drops.
- Reach target volume over 4 to 6 weeks for a cold domain; faster if you have an established parent domain.
Frequently asked questions#
How long does email warm-up take?
Two to six weeks depending on target volume and whether the domain is brand new.
Do I need to warm up a shared IP?
The IP is already warm, but your domain is not. Domain warm-up still applies.