The method used to specify an unsubscribe group for an email depends on how you will be sending that email:
- When sending an SMTP message, add the group’s ID to the X-SMTPAPI header.
- When sending an email via the Web API v2, add the group’s ID in the
- When sending an email via the Web API v3, define the group’s ID in the
asm_group_id please make sure to only use integers as shown in our examples. Any other type could result in unintended behavior.
You may only specify one group per send, and you should wait one minute after creating the group before sending with it.
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To specify which groups to display on the Manage Preferences page of an email, add the group IDs to the X-SMTPAPI header of an SMTP message, or in the x-smtpapi parameter of a mail.send API call. If you omit the asm_groups_to_display header, your default groups is shown on the Manage Preferences page instead.
You can specify up to 25 groups to display.
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You can find your group IDs by looking at the Group ID column in the Unsubscribe Groups UI, or by calling the GET method of the groups resource.
- You can create Unsubscribe groups via the API V3 > Unsubscribe Groups Endpoint.