[grinich]

Michael from Inbox here.

Short answer: we're working on it.

Any pushing-based API really needs to gracefully degrade to polling in case messages are lost. So we decided to first make sure the semantics of the delta sync API were great.

Under the hood we actually use features like IDLE or MS Exchange Ping, so our push updates will also be immediate. The benefit of the delta sync API is that you can query deltas (obviously), which isn't supported by IMAP.

[jkarneges]

Love the sync API. It should be easy to add long-polling support to the sync endpoint, or use the sync endpoint when any other push delivery mechanisms fail.

You might check out https://fanout.io/ which makes it easy to create realtime APIs. (disclaimer: I'm from Fanout)