Regulated data (health, financial, personal) requires protection in transit at minimum, and increasingly proof of it.
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#
- Enforce TLS 1.2+ on inbound and outbound connections.
- Publish MTA-STS to prevent downgrade attacks.
- For regulated content, use S/MIME or a secure-message portal with recipient authentication.
- Log and report TLS failures via TLS-RPT.
Frequently asked questions#
Is Gmail encrypted?
Gmail uses TLS in transit and encryption at rest. End-to-end encryption requires S/MIME (Workspace Enterprise) or client-side encryption.