Wikipedia
Push-IMAP
Push-IMAP, which is otherwise known as P-IMAP or Push extensions for Internet Message Access Protocol, is based on IMAPv4 Rev1 (RFC 3501) but contains additional enhancements for optimization in a mobile setting. It was developed by Oracle and other partners, and it was submitted as input to the Lemonade Profile IETF Working Group; however, P-IMAP was not included in the Lemonade Profile (RFC 4550).