The changelog provides a list of dated updates, each of which contains a number of potentially backwards-incompatible changes. There is no explicit versioning in the API at this time; all changes will be either compatible or breaking. (If I attempt any brittle changes to the API that may break current implementations, I'll be sure to add version gates.)
Took the ability to send specific emails to subscribers out of beta; added `/v1/subscribers/<id>/send-reminder`, which allows you to send reminders to your subscribers to confirm their email address.
Added support for Exports via the `/v1/exports` endpoint.
Added support to set and retrieve metadata on Emails.
Added deletion and update abilities to the Scheduled emails endpoint, giving you much more programmability than the hitherto append-only state of the world.
Added a deletion endpoint to the Images endpoint, allowing you to delete unused images.