int imap_ping(int imap_stream);
Returns true if the stream is still alive, false otherwise.
imap_ping() function pings the stream to see it is still active. It may discover new mail; this is the preferred method for a periodic "new mail check" as well as a "keep alive" for servers which have inactivity timeout. (As PHP scripts do not tend to run that long, i can hardly imagine that this function will be usefull to anyone.)