Free One-Click Unsubscribe Validator

Verify List-Unsubscribe and List-Unsubscribe-Post headers meet Gmail, Yahoo, and Outlook 2025 requirements for bulk senders.

One-Click Unsubscribe Validator

Verify RFC 8058 compliance and Gmail/Yahoo/Outlook 2025 bulk sender requirements

Email Headers

Add these headers to every marketing email:

List-Unsubscribe: <https://example.com/unsubscribe?id=TOKEN> List-Unsubscribe-Post: List-Unsubscribe=One-Click

Key Requirements

Essential requirements for RFC 8058 compliance and Gmail/Yahoo/Outlook bulk sender standards (2025).

HTTPS Only

Unsubscribe URLs must use HTTPS protocol. HTTP URLs are not allowed for security reasons.

POST Endpoint

Must accept POST requests with List-Unsubscribe=One-Click parameter and return 2xx status code.

No User Interaction

Immediate unsubscribe without requiring login, CAPTCHA, or confirmation page.

Unique Tokens

Different token per recipient for security and tracking (e.g., ?id=TOKEN or ?token=ABC123).

2-Day Processing

Endpoint must respond within 2 seconds. Honor all unsubscribe requests within 2 business days.

Marketing Emails Only

Required for promotional/marketing emails from bulk senders (5,000+ emails/day). NOT required for transactional emails.

Why This Matters

Understanding the importance of one-click unsubscribe for your email program success in 2025 and beyond.

2025 Enforcement: Gmail, Yahoo & Microsoft

Since February 2024, Gmail and Yahoo strictly enforce one-click unsubscribe (RFC 8058). In May 2025, Microsoft Outlook joined with identical requirements. Bulk senders (5,000+ emails/day) must comply or face rejection/spam placement. Yahoo heavily enforced in April 2025, causing open rates to drop from 20-25% to under 5% for non-compliant senders.

Transactional vs Marketing Emails

One-click unsubscribe is ONLY required for promotional/marketing emails. Transactional emails (order confirmations, password resets, shipping notifications) are exempt. However, marketing emails without proper one-click unsubscribe will be blocked or sent to spam across all major ISPs.

Deliverability & Reputation Impact

Implementing RFC 8058 improves sender reputation and reduces spam complaint rates (must stay below 0.3%, ideally below 0.1%). Better reputation leads to higher inbox placement, improved engagement rates, and overall email program success. Non-compliance results in immediate deliverability problems.

Common Implementation Mistakes

Avoid these common errors when implementing one-click unsubscribe functionality.

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Requiring login to unsubscribe

Users must be able to unsubscribe without authentication

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Using HTTP instead of HTTPS

All unsubscribe URLs must use secure HTTPS protocol

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Slow endpoint response times

Endpoints taking longer than 2 seconds will fail compliance

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Missing List-Unsubscribe-Post header

Both List-Unsubscribe and List-Unsubscribe-Post headers are required

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Not honoring unsubscribes immediately

Unsubscribed users should stop receiving emails within 2 business days

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Adding one-click to transactional emails

One-click unsubscribe is ONLY for marketing emails, not transactional (receipts, password resets, etc.)

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Ignoring spam rate thresholds

Spam complaint rate must stay below 0.3% (ideally below 0.1%) or deliverability will suffer