Maildown is a REST API client service for sending transactional emails that supports markdown syntax. You can simply pass the subject line, recipients and message content, in markdown format, to the API and it will generate and send cleanly formatted emails to your recipients with very little effort.
The Maildown API provides a single REST endpoint for sending messages. You'll need an API token in order to authenticate, which you can retrieve at any time from your Dashboard.
You'll also need to verify your email address before you can send emails using Maildown, as proof of ownership. You'll be prompted to do this as soon as you register for a Maildown account, and will need to complete the verification process before you can use the API.