iPhone and IMAP IDLE (part 2)
By chienr on Feb 21, 2008
This is a follow-up and correction to my previous post: iPhone supports IMAP IDLE.
After more testing, turns out iPhone does not support IMAP IDLE (on a Wi-Fi connection, firmware 1.1.3), it instead Auto-Checks every 2-5 minutes despite the Setting says don't. I verified this by enabling IMAP telemetry in Dovecot 1.0 through its rawlog facility. Even though the server advertises IDLE in its CAPABILITY response, iPhone's client never issues the IDLE command.
Is that a loss? Probably not. According to this thread, beta testers of the iMapIdle utility report significant battery drain while IDLE runs on a Wi-Fi connection. On an EDGE connection, the drain is not as bad. But when iPhone switches between Wi-Fi and EDGE, the IDLE session gets dropped. For these reasons, I can see why Apple designers chose to not implement IMAP IDLE on iPhone.