Non-compliant mail is rejected or filtered at the two largest consumer mailbox providers. Enforcement has tightened each year since.
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#
- Publish SPF and DKIM, and a DMARC record at minimum p=none with aligned From domain.
- Add List-Unsubscribe headers and honor requests within two days.
- Use a valid forward and reverse DNS (PTR) for sending IPs.
- Monitor spam rate in Postmaster Tools and keep it under 0.1%.
- Send from a subdomain with its own reputation for marketing.
Frequently asked questions#
What happens if I do not comply with Gmail bulk sender rules?
Temporary failures (4xx) escalating to rejections, and reduced inbox placement. Gmail announced enforcement in stages through 2024 and beyond.