Add a one-click List-Unsubscribe header
The List-Unsubscribe header lets recipients unsubscribe directly from the inbox UI. As of Gmail and Yahoo's 2024 bulk-sender rules, one-click unsubscribe (RFC 8058) is mandatory for senders above ~5,000 messages/day — and a strong positive signal for everyone.
Why mailbox providers enforce this
Mailbox providers would rather a recipient unsubscribe than mark you as spam, because spam complaints poison your reputation for everyone. Offering frictionless unsubscribe lowers your complaint rate, which is the single metric Gmail and Yahoo weight most heavily after authentication.
How to fix it
- Add both headers: List-Unsubscribe with a mailto: and https: option, and List-Unsubscribe-Post: List-Unsubscribe=One-Click.
- The https endpoint must unsubscribe the user on a single POST — no login, no confirmation page.
- Process unsubscribes within 2 days, as the rules require.
- Keep the visible in-body unsubscribe link too — the header complements it, doesn't replace it.
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FAQ
Do transactional emails need List-Unsubscribe?
The bulk-sender mandate targets promotional/marketing mail. Pure transactional mail (receipts, password resets) is generally exempt, but adding the header never hurts.
Does missing it really send me to spam?
For bulk senders past the threshold, yes — Gmail and Yahoo will filter or reject. Below the threshold it's a soft negative signal, not an automatic block.
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