After receiving a notification from the mail server, the WAP server sends an XML message by SMS to the mobile device which then triggers the mail client to eventually FETCH the new message headers or BODY part (according to predefined configuration settings).

EMN is used as an outband notification mechanism in the Lemonade Notification draft.

If you know how to use Kannel, there might be a way to receive messages from an SMTP server, extract the relevant part, construct an EMN XML message and turn it into an HTTP POST – assuming the phone is compatible, of course.

Has anyone tried to capture traffic between an iphone and the yahoo servers to verify this?

And P-IMAP is a dead I-D, pushed by Oracle, which ended up being cherry-picked for value for Lemonade, which does use IDLE, and is deployed, as well as being an IETF Proposed Standard.

Now. Your article suggests that IDLE is inherently un-robust – not true. The issue is that with a NAT in the way, a TCP connection may be severed for no good reason. TCP survives the lower layer dropping out just fine. From a technical standpoint, then, a TCP connection running dormant is the ideal solution. There’s nothing magical about using TCP and IDLE to provision push notifications, as compared to some other method.

Microsoft’s solution relies on repetitive HTTP queries, which cost battery power, and, for many users, actual real money. It’s still client provisioned, it’s just much worse.