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POST

Path Parameters

string
required
The unique identifier of the reply thread to respond to.

Body Parameters

string
required
The reply message body (plain text or HTML).
string
Optional subject line override. Defaults to Re: <original subject>.

Response

object

Errors

Rate Limit

  • 100 requests per minute, per API key. Fixed 60-second window.
  • Every response includes X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset (unix epoch seconds).
  • A 429 response includes a Retry-After header (seconds until the bucket resets).
For client-side patterns (Retry-After, exponential backoff, monitoring X-RateLimit-Remaining), see Rate Limiting.