Add subscribers to a list
Subscribes additional users to the list, without modifying existing subscriptions. If the list does not exist, it will be automatically created.
Path parameters
A unique identifier representing the list you wish to retrieve.
Headers
A unique key that makes this request idempotent. If Courier receives another request with the same Idempotency-Key, it returns the stored response from the first request without performing the operation again (including the original status code and any error). Use it to safely retry POST requests after network failures without risking duplicate sends. The key is scoped to this endpoint.
How long the idempotency key remains valid, as a Unix epoch timestamp in seconds or an ISO 8601 date string. Only applies when Idempotency-Key is provided. If omitted, the key is retained for 25 hours; the maximum is 1 year.