IMAP IDLE
Appearance
In e-mail technology, IDLE is an IMAP feature described in RFC 2177 that allows a client to indicate to the server that it is ready to accept real-time notifications.
Significance
The IDLE feature is significant from an engineering point of view for the reason that it allows IMAP e-mail users to see immediately any mailbox changes without having to undertake any action (eg clicking on a Refresh button).
Usage
IMAP4 servers that support IDLE will include this string in the result of their CAPABILITY command.