# Email invoice

Send invoice to customer via email.

## What happens

- Generates invoice PDF if not already generated
- Sends email with PDF attachment
- Logs email in activity feed

Endpoint: POST /invoices/{id}/send
Version: 1.0.0
Security: BearerAuth

## Path parameters:

  - `id` (string, required)
    Resource ID (UUID) or client key
    Example: "550e8400-e29b-41d4-a716-446655440000"

## Query parameters:

  - `by` (string)
    Specify lookup type for faster retrieval.
If omitted, defaults to looking up by ID first, then falls back to client key if not found.
Use by=key when you know you're providing a client key for best performance.
    Enum: "id", "key"

## Request fields (application/json):

  - `toEmails` (array, required)

  - `ccEmails` (array)

  - `subject` (string)
    Email subject (defaults to standard invoice subject)

  - `message` (string)
    Email body message

## Response 200 fields (application/json):

  - `success` (boolean)

  - `emailId` (string)

## Response 400 fields (application/json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message

## Response 401 fields (application/json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message

## Response 404 fields (application/json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message