POST Send Thread Message​
Send a message into an existing conversation from the Inbox, on the thread's own channel. The send runs inline (no queue); the message row is written as pending before the provider is called and updated to sent or failed, so a request that dies leaves a record. On a provider failure the response is 422 and still carries sent_message (with status: failed and error_message).
Text (message_type omitted or text): content is required (422 Write a message first. when blank).
- SMS: always allowed (no session window).
- WhatsApp 24-hour rule: free-form text is accepted only while the contact's last inbound message is less than 24 hours old (
session.has_active_session). Outside the window the call returns 409This WhatsApp conversation is outside its 24-hour window, so only an approved template can be sent.Send a template instead.
Template (message_type = template): WhatsApp only (422 on SMS threads). Needs template_name and optionally template_language (or language); the template must be approved for the current provider (422 Pick an approved template.). Variables in template_variables are rendered against the thread's linked contact. The thread needs a phone number, and the provider must support templates (409 otherwise). Templates are allowed inside or outside the 24-hour window. The stored message content is the template body text.
409 is also returned when Pro is inactive or the channel is not configured/active. This endpoint does not check the thread's consent status; the profile-level POST /messaging/subscribers/{id}/send does. PRO (FluentCampaign Pro Messaging module).
Required capability: fcrm_read_emails or fcrm_manage_emails — which one applies depends on the action being performed.
Enforced by InboxPolicy::verifyRequest(), the policy default for this route group.
Requires: FluentCampaign Pro with the Messaging module enabled. While no messaging channel (SMS or WhatsApp) is switched on the route is not registered at all and returns a 404.
Authorizations​
WordPress Application Passwords — use Basic auth with your WordPress username and an application password in the format: username:application_password
Parameters​
Path Parameters
Message thread ID.
Request Body​
Responses​
Message sent.