All requests must be authenticated using your API key. You can manage your API key within the Mailosaur UI; navigate to Your account and select API Access.
When using one of our Client Libraries your key will be set in code, and then automatically sent in each request.
If you need to make your own HTTP requests, note that API authentication is performed via HTTP Basic Auth. Provide your API key as the basic auth username value. You do not need to provide a password.
All API requests must be made over HTTPS. Calls made over plain HTTP will fail. API requests without authentication will also fail.