Cold email glossary

What is One-click unsubscribe?

The RFC 8058 List-Unsubscribe headers that let a recipient opt out with one click from their mail client; required by Gmail and Yahoo for bulk senders.

Two headers — List-Unsubscribe: <https://...> and List-Unsubscribe-Post: List-Unsubscribe=One-Click — let Gmail, Yahoo and others show an unsubscribe control at the top of the message. Since 2024, bulk senders must include them and honour requests within two days. The point for cold email is complaint avoidance: a recipient with an obvious unsubscribe uses it; one without reports spam.

Related terms

GlossarySpam rate (complaint rate)The share of your delivered mail that recipients mark as spam; Gmail says keep it below 0.3% and ideally under 0.1%.GlossarySuppression list (blocklist)Addresses and domains that must never be emailed — unsubscribes, complaints, bounces, competitors — enforced at import, enrolment and send time.

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