post

Creates a new message for a specific application. Messages can be sent to the candidate (outbound) or recorded as responses from the candidate (inbound). Supports both text (SMS) and email message types.

Message Direction:

• 'to_candidate': Outbound messages sent to the candidate (e.g., from AI system)
• 'from_candidate': Inbound messages/responses from the candidate

Message Delivery Control:

• is_sent_by_vendor: default true if not sent in payload
• is_sent_by_vendor=true: Vendor handles message delivery
• is_sent_by_vendor=false: Apploi sends the message via SMS/Email infrastructure

Email Requirements: When message_type is 'email', the 'subject' field is required.

Authentication: Requires valid x-api-key header.