Glossary

What is one click unsubscribe?

One click unsubscribe lets a recipient stop your emails with a single button in their mail app, without opening a page or writing back. It works through two email headers, List-Unsubscribe and List-Unsubscribe-Post. Google and Yahoo ask for it on marketing and subscribed messages, alongside a visible unsubscribe link in the body.

Published by Sellinger AI. Numbers and settings checked on 24 October 2026 against the fact register. Report an error.

How does it work?

Google's sender guidelines give the two headers as List-Unsubscribe-Post: List-Unsubscribe=One-Click and List-Unsubscribe: followed by a link. When the recipient clicks unsubscribe in Gmail or another mail app, the app sends a request to that link, and your system records the opt out. Yahoo accepts a mailto method and highly recommends the POST method.

Does cold email need it?

Both providers word the rule for marketing and subscribed messages. A one to one cold email is not clearly a newsletter, and neither page says how it is treated. The practical reading: if your message sells something to people who did not sign up, assume the rule can apply. Offering a clean way to stop also keeps people from pressing the spam button, which costs you far more.

Read the full comparison in Google and Yahoo bulk sender rules, read 19 October 2026.

What else should the opt out route do?

Work for a reasonable time after sending.
Be honoured quickly. Yahoo asks for 2 days, and the US CAN-SPAM Act sets 10 business days.
Apply everywhere: one opt out should stop every campaign and mailbox, not just the one it came from.

How Sellinger handles it

Cold email can carry an unsubscribe line and the standard one click unsubscribe headers (List-Unsubscribe and List-Unsubscribe-Post). It is a per mailbox setting. The setting is off by default, so switch it on for any mailbox that sends cold email.

When a contact replies with an opt out such as STOP or unsubscribe, in English, Bulgarian or German among other forms, the contact goes on the team's suppression list, the agent stops and the lead is closed out. A weak or unclear phrase never writes the permanent record: the agent stops and a person decides. Before every send on email, LinkedIn and WhatsApp, the platform checks the team's suppression list and refuses the send when the contact is on it or when the check cannot be completed.

Common questions

Is a visible unsubscribe link still needed?

Yes. Google and Yahoo both ask for a visible link in the body as well as the headers.

Does replying stop work as an unsubscribe?

In Sellinger, yes: a clear opt out reply adds the contact to the suppression list and the agent stops.

Do I need it for LinkedIn messages?

No. The headers are an email mechanism. On LinkedIn, a reply asking to stop is the opt out.

Sources and method

Google email sender guidelines and Yahoo Sender Hub, read 19 October 2026 for the linked blog post. Sellinger behaviour from the fact register, checked 24 October 2026.