One Click Unsubscribe Requirements

What is actually required

Gmail and Yahoo introduced requirements for bulk senders, generally understood as those sending upwards of 5,000 messages a day to their users. The main ones are authenticating your domain, keeping spam complaints low, and supporting one-click unsubscribe that is honoured within a couple of days.

One-click means a List-Unsubscribe header plus List-Unsubscribe-Post, so the mailbox provider can submit the opt-out on the recipient's behalf without them visiting your site. The provider will call that endpoint.

The trap: advertising a header you do not honour

Sending List-Unsubscribe-Post tells the provider it may POST to your URL. If that endpoint does not exist, the request quietly fails and you have claimed support for something you do not have. That is a worse position than omitting the header, because now the provider has evidence you are not honouring opt-outs.

It also pushes people toward the report-spam button, which is the single most damaging signal for a sending domain. When unsubscribing does not work, complaining is the only option a recipient has left.

Frequently Asked Questions

What is one-click unsubscribe?

A List-Unsubscribe header combined with List-Unsubscribe-Post that lets a mailbox provider submit an opt-out on the recipient's behalf, without them visiting your site.

Who has to support it?

Bulk senders, generally those sending upwards of 5,000 messages a day to Gmail or Yahoo. The opt-out is expected to be honoured within about two days.