Gmail has always had a slightly different take on email ever since its inception. Instead of traditional folders, Google imagined a new way of leveraging its search product for the communication medium. But with that different take came a lot of work-arounds needed to fit non-traditional uses into the IMAP standard.
With the release of the new Gmail API at this year's developers conference, Google is taking steps to give more and better access to its email platform.There will still be the basic things like being able to send and receive email, but also better control over labels and better search.
It doesn't appear, however, that the new Gmail API is aiming to replace IMAP just yet. Listed on the API page is a note that it shouldn't be used for full-fledged email client access.
From Google's announcement of the API is a little deeper explanation.
In contrast to IMAP, which requires access to all of a user’s messages for all operations, the new API gives fine-grained control to a user’s mailbox. For example, if your app only needs to send mail on behalf of a user and does not need to read mail, you can limit your permission request to send-only.
To keep in sync, the API allows you to query the inbox change history, thereby avoiding the need to do "archaeology" to figure out what changed.
There are already a lot of apps that use Gmail in non-traditional ways, but many are pushing Gmail beyond its current limits, resulting in a buggy experience. Popular add-ons like Boomerang are hugely useful, allowing you to schedule messages to send in the future, but are a little wonky to operate in practice.
Another top extension for Gmail is Play My Inbox. The app turns a user's inbox into a jukebox by scanning messages to find threads containing songs. It then displays the songs in new visual manner. With the new Gmail API, the clever use cases should only increase from here on out.