Bounce rate is the fastest way to burn an outbound domain. Unverified purchased lists routinely bounce 10 to 30 percent.
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#
- Verify every address through an API before it enters a sequence.
- Segregate catch-all domains and send to them at lower volume.
- Refresh verification for any lead older than 90 days.
- Enrich with 3 to 5 data points that drive the opening line.
Frequently asked questions#
What bounce rate is safe for cold email?
Under 2 percent. Above 5 percent, pause and re-verify the list before continuing.