Push-IMAP, which is otherwise known asP-IMAP orPush extensions forInternet Message Access Protocol, is an email protocol designed as a faster way to synchronise a mobile device like a PDA orsmartphone to an email server.
It was developed byOracle and other partners, and based onIMAP with additional enhancements for optimization in a mobile setting. It was submitted as input to theLemonade ProfileIETF Working Group - but was not included in the resulting RFC 4550.
The protocol was designed to provide for a secure way to automatically keep communicating new messages between a server and a mobile device like aPDA orSmartphone. It should reduce the time and effort needed to synchronize messages between the two by using an open connection that is kept alive by some kind of heartbeat. To reduce necessarybandwidth, it uses compression and commandmacros.Additionally, P-IMAP features a mechanism for sending email that is derived from (but not identical to)SMTP, and so a rich email service is provided using a single connection.
P-IMAP should not be viewed as an alternative to theIMAP IDLE command (RFC 2177). In fact, IDLE is one of the required mechanisms for a P-IMAP server to notify the client (optional notifications areSMS orWAP Push).
Although they are both based on IMAP, theYahoo! Mail andiCloud push email services foriPhone do not use a standard form of P-IMAP. Yahoo! Mail uses a specialUDP message to trigger an email synchronization, whileApple's iCloud push email uses a variant ofXMPP.[1]