Every request must be sent over secure connection (HTTPS). Unsecure requests are redirected to HTTPS and thus can fail.
API user has to authenticate each API request with Basic-Auth.
A quick example of doing Basic-Auth with Python Requests:
>>> import requests >>> from requests.auth import HTTPBasicAuth >>> requests.get('https://<subdomain>.sendsmaily.net/api/v2', auth=HTTPBasicAuth('api-user', 'api-password')) <Response >