> ## Documentation Index > Fetch the complete documentation index at: https://docs.mailchannels.com/llms.txt > Use this file to discover all available pages before exploring further. # Unsubscribe > Learn how to give recipients a one-click way to opt out. MailChannels supports two ways to let recipients opt out of future email: * An **unsubscribe link** that you place inside the message body. * **List-Unsubscribe headers** that email clients render as a native unsubscribe control. ## Unsubscribe link Insert the `mc-unsubscribe-url` placeholder anywhere in your `text/html` or `text/plain` content. At render time, MailChannels replaces it with a unique URL that opens a one-click unsubscribe page hosted by MailChannels. To use the placeholder: * The content part must set `template_type` to `mustache`. * Each personalization must contain exactly one recipient, so the generated URL is unique to that recipient. Only `text/html` and `text/plain` content parts are supported. The placeholder is ignored in other content types. ### HTML content Place the placeholder in the `href` of an `` element so it renders correctly across email clients: ```bash cURL theme={null} #!/usr/bin/env bash set -u : "${MAILCHANNELS_API_KEY:?Set MAILCHANNELS_API_KEY before running}" : "${FROM_EMAIL:?Set FROM_EMAIL (must be on a Domain-Lockdown-authorized domain)}" : "${TO_EMAIL:?Set TO_EMAIL}" curl -X POST https://api.mailchannels.net/tx/v1/send \ -H "Content-Type: application/json" \ -H "X-Api-Key: $MAILCHANNELS_API_KEY" \ -d @- <Unsubscribe", "template_type": "mustache" } ] } JSON ``` ```javascript Node.js theme={null} import { MailChannels } from "mailchannels-sdk"; const { MAILCHANNELS_API_KEY, FROM_EMAIL, TO_EMAIL } = process.env; if (!MAILCHANNELS_API_KEY) throw new Error("Set MAILCHANNELS_API_KEY before running"); if (!FROM_EMAIL) throw new Error("Set FROM_EMAIL (must be on a Domain-Lockdown-authorized domain)"); if (!TO_EMAIL) throw new Error("Set TO_EMAIL"); const mailchannels = new MailChannels(MAILCHANNELS_API_KEY); const { data, error } = await mailchannels.emails.send({ from: { email: FROM_EMAIL, name: "Your Name" }, to: { email: TO_EMAIL, name: "Recipient" }, subject: "Hello from MailChannels", html: "Unsubscribe", template: { type: "mustache" }, }); if (error) { console.error("Send failed:", error); process.exit(1); } console.log(data); ``` ```python Python theme={null} import os import sys import mailchannels if not os.environ.get("MAILCHANNELS_API_KEY"): sys.exit("Set MAILCHANNELS_API_KEY before running") from_email = os.environ.get("FROM_EMAIL") to_email = os.environ.get("TO_EMAIL") if not from_email: sys.exit("Set FROM_EMAIL (must be on a Domain-Lockdown-authorized domain)") if not to_email: sys.exit("Set TO_EMAIL") response = mailchannels.Emails.send( { "from": {"email": from_email, "name": "Your Name"}, "subject": "Hello from MailChannels", "content": [ { "type": "text/html", "value": "Unsubscribe", "template_type": "mustache", }, ], "personalizations": [ {"to": [{"email": to_email, "name": "Recipient"}]}, ], } ) print(response) ``` ```php PHP theme={null} emails->send([ 'from' => ['email' => $from_email, 'name' => 'Your Name'], 'subject' => 'Hello from MailChannels', 'content' => [ [ 'type' => 'text/html', 'value' => "Unsubscribe", 'template_type' => 'mustache', ], ], 'personalizations' => [ ['to' => [['email' => $to_email, 'name' => 'Recipient']]], ], ]); print_r($response->toArray()); ``` ### Plain text content Include the placeholder inline: ```bash cURL theme={null} #!/usr/bin/env bash set -u : "${MAILCHANNELS_API_KEY:?Set MAILCHANNELS_API_KEY before running}" : "${FROM_EMAIL:?Set FROM_EMAIL (must be on a Domain-Lockdown-authorized domain)}" : "${TO_EMAIL:?Set TO_EMAIL}" curl -X POST https://api.mailchannels.net/tx/v1/send \ -H "Content-Type: application/json" \ -H "X-Api-Key: $MAILCHANNELS_API_KEY" \ -d @- <emails->send([ 'from' => ['email' => $from_email, 'name' => 'Your Name'], 'subject' => 'Hello from MailChannels', 'content' => [ [ 'type' => 'text/plain', 'value' => 'To unsubscribe, visit: {{mc-unsubscribe-url}}', 'template_type' => 'mustache', ], ], 'personalizations' => [ ['to' => [['email' => $to_email, 'name' => 'Recipient']]], ], ]); print_r($response->toArray()); ``` ## List-Unsubscribe headers Clients such as Gmail and Apple Mail render a native **Unsubscribe** control when a message carries `List-Unsubscribe` and `List-Unsubscribe-Post` headers. We automatically add both headers when the `transactional` field is set to **false** in the send request — **unless you include your own `List-Unsubscribe` header, in which case we use yours and don't add ours.** When `transactional` is false, the following conditions must also be met: * Each personalization contains **exactly one recipient** * The email is [DKIM signed](/email-api/configuring-dkim)