Configuration

Default Behavior

Set your API key in the constructor and all methods use it automatically:

const outbound = new Outbound({ apiKey: 'mu_outbound_...' });

Constructor Options

You can customize HTTP behavior by passing a config object:

const outbound = new Outbound({
  apiKey: 'mu_outbound_...',      // Default API key (optional if provided per call)
  baseUrl: 'http://localhost:3000', // For local development
  timeout: 30_000,    // Request timeout in ms (default: 30s)
  maxRetries: 3,      // Retry attempts on 429/5xx (default: 3)
  retryDelay: 1000,   // Initial backoff delay in ms (default: 1s)
});

Options Reference

Option	Type	Default	Description
apiKey	string	—	Default API key (optional if provided per call)
baseUrl	string	Production URL	API base URL (override for local dev)
timeout	number	30000	Request timeout in milliseconds
maxRetries	number	3	Max retry attempts on 429 and 5xx errors
retryDelay	number	1000	Initial retry delay in ms (doubles each attempt)

API Key

The API key can be set in two places:

1. Constructor (default) — used for all calls unless overridden
2. Per call — passed as the last argument via { apiKey }, takes priority

Single tenant — set once

const outbound = new Outbound({ apiKey: 'mu_outbound_...' });

await outbound.email.send({ /* ... */ });          // uses constructor key
await outbound.dashboard.quota();                  // uses constructor key

Multi-tenant — override per call

const outbound = new Outbound(); // no default key

await outbound.email.send({ /* ... */ }, { apiKey: tenantAKey });
await outbound.email.send({ /* ... */ }, { apiKey: tenantBKey });

Mixed — default with overrides

const outbound = new Outbound({ apiKey: tenantAKey });

await outbound.email.send({ /* ... */ });                        // uses tenantAKey
await outbound.email.send({ /* ... */ }, { apiKey: tenantBKey }); // uses tenantBKey

If no API key is available (neither in the constructor nor per call), an AuthenticationError is thrown.

Getting your API key

1. Log in to the Outbound dashboard
2. Navigate to Settings > API Keys
3. Generate a new key — it starts with mu_outbound_

WARNING

Keep your API key secret. Never commit it to version control. Use environment variables or a secrets manager.

Retry Behavior

The SDK automatically retries failed requests with exponential backoff:

• Retried: 429 Too Many Requests and 5xx Server Error
• Not retried: 4xx Client Errors (400, 401, 403, 404, 409)
• Backoff: 1s → 2s → 4s (doubles each attempt)
• 429 with Retry-After: Respects the server's Retry-After header

// Disable retries
const outbound = new Outbound({ maxRetries: 0 });

// Aggressive retries
const outbound = new Outbound({ maxRetries: 5, retryDelay: 500 });

Local Development

When developing against a local Outbound API instance:

const outbound = new Outbound({
  apiKey: 'mu_outbound_...',
  baseUrl: 'http://localhost:3000',
});