The MailerLite Python SDK by Larry Brid is a work in progress that aims to interact with email marketing features of the API. It contains resources to work with campaigns, subscribers, and subscribers lists.
DokDok, a Montreal-based startup, has had an email attachment management application on Google Apps some time. To make this work, it made an API to use internally that intelligently uses email accounts as if they were datastores. Recently, the company announced that this API would be renamed Context.IO and available to all.