Gmail and Yahoo require one-click unsubscribe for bulk senders, and every anti-spam law requires a working opt-out. Easy opt-out also lowers complaints.
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#
- Include a visible unsubscribe link in every marketing message.
- Add List-Unsubscribe and List-Unsubscribe-Post headers so providers show a native unsubscribe button.
- Process opt-outs immediately; the legal maximum is 10 business days in the US, but providers expect 2 days.
- Never require login or more than one click to unsubscribe.
List-Unsubscribe: <https://example.com/u/abc123>, <mailto:unsub+abc123@example.com>
List-Unsubscribe-Post: List-Unsubscribe=One-ClickFrequently asked questions#
What is one-click unsubscribe?
An RFC 8058 header pair that lets the mailbox provider send a POST to your endpoint when a user clicks Unsubscribe in the client, with no landing page.