Send a transactional email

Send a transactional email

Sends one transactional email to a person, from a template filled with your message data or from a subject, body and sender you pass, creating the person if needed.

Note: The CLI sends with a service-account token and needs --environment-id, the workspace ID; production code should send with an App API key.

Set up

Use the first option your agent supports.

CLI (official)

Install the command, then confirm it runs.

npm install -g @customerio/cli
cio --version

Run cio send email.

Set $CIO_TOKEN in your environment first (get a key: https://fly.customer.io/settings/api_credentials?keyType=service_accounts).

API (official)

• Base URL: https://api.customer.io
• Endpoint: POST /v1/send/email
• Auth: send the header Authorization: Bearer $CUSTOMERIO_API_KEY
• Get a key: https://fly.customer.io/settings/api_credentials?keyType=app
• Docs: https://docs.customer.io/integrations/api/app/

Before anything else, confirm access with the cheapest read-only call, like a list or a search. Never send or change anything to test access.

Rules

• Ask the user before anything that sends messages, costs money, or changes data, and say how many records it touches. One approval covers a batch the user has seen.
• Never print API keys.