[dead78]

is there some sort of magic involved? how does the phone know the check for email without an active connection? seems as if there would have be to be some contact between the phone and my gmail account before gmail could notify the Pre as to the presence of new email.

[Minsc]

Well remember that there is a data connection that exists here... Even though it may be dormant, there is still a connection between your Pre and the mail server. When new mail arrives, the mail server uses that data connection to "push" the mail to the Pre. (or to notify the Pre that new mail is waiting, at which point the Pre initiates the fetch - I'm not sure in the case of IMAP how that works, but either way the mail server is the one that's responsible for notifying the device)

[Jayrot]

Also, ghostmagic.

[dead78]

meaning there's an ongoing open connection between the pre and gmail at all times?

[Jayrot]

en.wikipedia.org/wiki/Push_email

[hparsons]

I don't know about IMAP idle, but other systems I've used basically send a SMS message to the device that tells the client (on the device) that there is a new email. This avoids the constant connectivity issue.

This is (basically) the way BES (BlackBerry Enteriprise Server), Novell's GroupWise Mobile Server, and EAS all work.

This is from Microsoft's web site:

An event is generated in a user's Exchange account when a new message arrives. This event causes a Short Message Service (SMS) notification to be sent to the user's device. The device synchronizes in the background. The user data is updated to the most current information, with no intervention on the part of the user.

The notification is sent as an SMS control message to the device. It is different from a regular SMS notification, because it does not appear as an SMS message in the Inbox. The SMS router and Exchange ActiveSync on the device process the notification. The notification itself does not carry any sensitive data.

Notifications can be sent from Exchange Server 2003 directly to the SMS address of the device, or through an aggregator (for example, a corporate service provider) configured by the Exchange administrator. For notifications to be sent to the SMS address of the device, the administrator must create an SMTP carrier in Exchange System Manager.

Note: Using this systems means that there is not a constant connection to the server. The SMS basically "wakes up" the client to go get the new information.

[dead78]

that's interesting. has it been confirmed that that's the system the Pre is using?

and also, how does it know where to send the SMS. it's not as if my phone number is listed anywhere on gmail.

[xandrake]

He's not asking about exchange push, gents.He's basically asking about p-imap (IMAPv4 rev.1).

Here is a starting point.

http://tools.ietf.org/internet-draft...-p-imap-12.txt

[SuperJason]

It's not using SMS, that was the old way of doing it and is being phased out.

For Google, it's using Imap Idle. It makes a connection, and issues an idle command which basically says "I'm going to stay connected, let me know if something happens".

[hparsons]

that's interesting. has it been confirmed that that's the system the Pre is using?

and also, how does it know where to send the SMS. it's not as if my phone number is listed anywhere on gmail.

The Pre uses different protocols, depending on what you've setup for a particular account.

• EAS works the way I described above.
• Pop3 and regular IMAP don't do un-initiated updates, you have to poll the server.
• I'm not sure how IMAP Idle works.

I've never examined the details of the initial EAS setup, but I suspect that when you do the initial sync, you're sending an SMS from your phone to the server, and it gets your information from that.

[hparsons]

He's not asking about exchange push, gents.He's basically asking about p-imap (IMAPv4 rev.1).

Here is a starting point.

Push-IMAP - Wikipedia, the free encyclopedia

You're right, sorry I missed the "(imap)" in the OP.

[dead78]

It's not using SMS, that was the old way of doing it and is being phased out.

For Google, it's using Imap Idle. It makes a connection, and issues an idle command which basically says "I'm going to stay connected, let me know if something happens".

ah thanks...so this will actually drain the battery down

people on here made it sound like the phone has no open connection and just sort of intuits when there's no email

[SuperJason]

That's known as "magic" :-). Just think about it logically, for the phone to know something, it has to either poll, or stay connected (at some layer at least). At some level SMS has to be doing the same thing. Obviously when they're not piggybacking on some other notification system such as SMS, it has to create a separate connection. If it was really a problem there would be ways to mitigate that.

It doesn't use a lot of battery. I have mine connected to exchange and imap idle, and I can easily get through a day with mildly heavy use.

[dead78]

That's known as "magic" :-). Just think about it logically, for the phone to know something, it has to either poll, or stay connected (at some layer at least). At some level SMS has to be doing the same thing. Obviously when they're not piggybacking on some other notification system such as SMS, it has to create a separate connection. If it was really a problem there would be ways to mitigate that.

It doesn't use a lot of battery. I have mine connected to exchange and imap idle, and I can easily get through a day with mildly heavy use.

for me the problem is that I'm working in an area where my data signal isn't very good. even though I'm using an airave, my phone is still utilizing EV, so I'd imagine having an open connection all day long with spotty data service isn't going to help anything.

what would you suggest I do?

[wynand32]

For a client to be "connected," that doesn't mean that it's literally sending/receiving data in a continuous stream. It means that a server has been informed that a client is standing by ready to receive information (and that the server therefore has the client's IP address). Thus, the server can "push" email to the client because it knows that the client's out there waiting, and where it is. And all the client has to do is listen on the relevant port, and then respond when it gets a packet.

That's my very basic understanding of it. Someone please correct me if I'm wrong.

[ryleyinstl]

en.wikipedia.org/wiki/Push_email

I saw nothing wrong with the info provided here

[SuperJason]

I would imagine that with spotty connection it may be continually re-establishing the connection when it's lost, which probably doesn't help things.

I was going to suggest using wifi, but I get the impression that it's only used when the phone isn't in standby.

Have you considered using a combination of Wifi and disable EVDO (is that possible?). I wonder if the airwave supports 1x data in addition to 1x voice.

Maybe someone can build a real solution based on my random thoughts :-)

[dead78]

I would imagine that with spotty connection it may be continually re-establishing the connection when it's lost, which probably doesn't help things.

I was going to suggest using wifi, but I get the impression that it's only used when the phone isn't in standby.

Have you considered using a combination of Wifi and disable EVDO (is that possible?). I wonder if the airwave supports 1x data in addition to 1x voice.

you're correct about wifi... once the phone goes into standby, evdo takes over.

I'm wondering if under the circumstances I'd be better off "polling" rather than "pushing" - this is all vaguely sexual, isn't it

[mrsyeltzin]

The Pre uses different protocols, depending on what you've setup for a particular account.

• EAS works the way I described above.
• Pop3 and regular IMAP don't do un-initiated updates, you have to poll the server.
• I'm not sure how IMAP Idle works.

I've never examined the details of the initial EAS setup, but I suspect that when you do the initial sync, you're sending an SMS from your phone to the server, and it gets your information from that.

After Exchange 2003 SP2 EAS no longer uses the SMS feature. Instead, it actually works a lot like IMAP idle where an http or https connection is made to the server when the phone registers on the network and then heartbeats (ICMP-like) are exchanged at timed intervals of I believe 12 minutes. If no emails are received before the 12 minutes are up, the heartbeat is sent to the phone (or from the phone?) and the session timer is reset. If an email is sent/received, then the timer is also reset. IMAP idle is very similar to this with exception to the timers and port. The main advantage EAS has over IMAP idle and Activesync v1 (with SMS) is that only the changes are synchronized - not the entire mailbox (folders, calendar, etc).

[dead78]

I'm sorry to ask this question, but how does one make use of EAS as opposed to IMAP or POP?