The suppression list gives you a programmatic way to ensure that certain email addresses are never contacted through Leadterra, regardless of which campaign they appear in. This is useful for honoring unsubscribe requests received outside of Leadterra, removing known bad addresses from deliverability protection, or syncing opt-out data from a CRM or preference center. Once an address is suppressed, it is excluded from sending across your entire workspace — not just a single campaign.
Endpoint
Authorization
All requests must include a valid API key in the Authorization header as a Bearer token.
Request Body
An array of email address strings to add to the suppression list. You may submit up to 1,000 addresses per request. Addresses that are already suppressed are silently ignored — they will not be counted in the suppressed response value and will not cause an error.
Example Request
Response Fields
The number of email addresses that were newly added to the suppression list in this request. Addresses that were already suppressed prior to this request are not counted.
Example Response
Suppression is workspace-wide and cannot be undone via the API. Once an address is added to your suppression list it applies to all current and future campaigns across your entire workspace. There is no API endpoint to remove an address from the suppression list — removals must be performed manually through the Leadterra dashboard under Settings → Suppression List.
Error Codes