Push IMAP vs. IDLE

Push IMAP vs. IDLE

IDLE is pure push-email. The IMAP server notifies the IMAP client when new messages arrive in real time and the client acts accordingly. The client does not poll the server for new mail and that new mail arrives at the client immediately. IDLE has been Standards Track (the highest industry status) since June of 1997! MDaemon supports IDLE but Outlook Connector does not at this time.

The problem with IDLE is that it was created 10 years ago when there were no hand-held devices to speak of. IDLE assumes that everyone wanting push-email is using the IMAP protocol on a powerful desktop over a fast LAN network. In short, it does not consider hand-held devices with little or no capability for storage, possibly not capable of running an IMAP client, and not on a fast network. As hand-held devices have gotten more powerful, have more local storage, and are connected to faster networks we are seeing a move toward IMAP in general and the IDLE extension in particular for push-email. It wasn't always the case that this was possible but now it is becoming the norm for hand-held devices.

P-IMAP is designed to be more hand-held device friendly. There are many commands added for doing things important to small devices with limited storage and connection speed - like managing attachments. Here is the synopsis for P-IMAP:

Push Extensions to the IMAP protocol (P-IMAP) defines extensions to the IMAPv4 Rev1 protocol [RFC3501] for optimization in a mobile setting, aimed at delivering extended functionality for mobile devices with limited resources.

At this time MDaemon does not support P-IMAP but it may be available in a future revision.