Transactional email is the best way to send, and deliver, relationship-driven emails. But most transactional email is hard. If you want to customize individual transactional emails, it involves a significant amount of engineering time, and you may end up losing control over the email.
Welcome to the HubSpot Transactional Email Single-Send API. You can create and send relationship-driven email from the same email interface within HubSpot, and use custom tokens that connect to your APIs to insert information directly from your own internal systems.
The single-send API combines the power integrating information from your own database and utilizing the same interface and infrastructure with HubSpot.
If you are interested in Transactional Email please talk to your Customer Success Manager about the Transactional Email Add-on.