# Send a single email

Send a single transactional or marketing email via REST API.

Simple API for sending emails with:
- Automatic queuing and delivery
- Built-in tracking (opens & clicks)
- Template variable support
- Custom headers
- Full bounce and complaint handling

Requirements:
- Verified sending domain
- Active customer account
- Valid API key

Auto-domain selection: If you don't specify a domain, we'll automatically use your first verified domain.

Endpoint: POST /api/send
Version: 1.0.0
Security: ApiKeyAuth

## Request fields (application/json):

  - `domain` (string)
    Sending domain (optional - auto-selects first verified domain if omitted)
    Example: "mail.yourdomain.com"

  - `from` (string)
    From email address (defaults to noreply@domain)
    Example: "hello@mail.yourdomain.com"

  - `to` (string, required)
    Recipient email address
    Example: "user@example.com"

  - `reply_to` (string)
    Reply-to email address
    Example: "support@yourdomain.com"

  - `cc` (array)
    CC recipients
    Example: ["manager@example.com"]

  - `bcc` (array)
    BCC recipients (hidden from other recipients)
    Example: ["archive@yourdomain.com"]

  - `subject` (string, required)
    Email subject line
    Example: "Welcome to our platform!"

  - `html` (string)
    HTML email body
    Example: "<h1>Welcome!</h1><p>Thanks for signing up.</p>"

  - `text` (string)
    Plain text email body (fallback for non-HTML clients)
    Example: "Welcome! Thanks for signing up."

  - `track_opens` (boolean)
    Enable open tracking (default: account setting)
    Example: true

  - `track_clicks` (boolean)
    Enable click tracking (default: account setting)
    Example: true

  - `headers` (object)
    Custom email headers
    Example: {"X-Campaign-ID":"campaign-123","X-User-ID":"user-456"}

  - `tag` (string)
    Tag for organizing emails
    Example: "welcome-series"

  - `metadata` (object)
    Custom metadata (stored but not sent in email)
    Example: {"user_id":"12345","signup_source":"homepage"}

## Response 200 fields (application/json):

  - `to` (string)
    Recipient email address
    Example: "user@example.com"

  - `submitted_at` (string)
    ISO 8601 timestamp when email was queued
    Example: "2024-01-15T10:30:00Z"

  - `message_id` (string)
    RFC 5322 Message-ID header value
    Example: "<650e8400-e29b-41d4-a716-446655440000@mail.yourdomain.com>"

  - `email_id` (string)
    Unique email ID for tracking
    Example: "650e8400-e29b-41d4-a716-446655440000"

  - `status` (string)
    Current email status
    Enum: "queued"

  - `message` (string)
    Success message

## Response 400 fields (application/json):

  - `error` (string)

  - `message` (string)

## Response 403 fields (application/json):

  - `error` (string)

  - `message` (string)

  - `reason` (string)

## Response 404 fields (application/json):

  - `error` (string)

  - `message` (string)

## Response 500 fields (application/json):

  - `error` (string)

  - `message` (string)