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  1. elyon's Avatar
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    Hey guys,

    I've heard conflicting reports about mail and battery life on the Pre. I've heard that it supports push email using IMAP IDLE, and that purportedly this should require less battery life than "pull" email, since the device will only transfer data with the server when you receive a new message.

    I've checked with my host (HostGator) and they said that they support IMAP IDLE. However, when I set my accounts (I'm using two on my phone) to "As it arrives" my battery life drains rapidly. When it is set to 15 minutes my battery life sustains itself.

    Have I misheard about push mail, and does it really tax your battery, or is this a sign that it is not actually doing push mail? Do I need to do something else?

    Thanks for the help. I'd love to have push mail enabled, but I can't have my phone dying on me because of it
  2. #2  
    If you are using an Exchange account and have it set to 'push', your battery will be fine (I have this for work). But if you are setting an IMAP account to 'push' you will suck the juice out of your battery very quickly. You are best off pulling your email at intervals (the longer the interval the better). I use push email for my two Exchange accounts, but have my other 3 email accounts (personal) set to pull email every 30 minutes to an hour.
  3. elyon's Avatar
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    Thanks for the help. That seems like what I'm experiencing. That sort of makes me wish that I had my own Exchange server
  4. #4  
    It depends on the IMAP server and the ISPs serving both your Pre (i.e. your cell carrier) and it.

    With IMAP idle the client (i.e. your Pre) leaves the TCP connection open so that the server can contact it whenever anything interesting happens in e-mail land. If no data is transmitted across a TCP connection for a long long time though, there's no way for the client to know if that's just because there's been no e-mail activity for a long long time, or if the server connection has in fact been dropped. (A properly closed connection involves a notification to the other end, a dropped connection doesn't.) To mitigate this, the client sends a small packet down the TCP connection every now and again that the server should respond to (essentially a ping). This is less data overhead than setting up a new connection, checking for mail, then closing it down again like POP e-mail does, and if the connection has in fact stayed open it is very efficient.

    The problem is if the connection is not actually staying open on the server, or along the way to the server (this is where the ISP's nats/routers and port forwarding configurations come into play); then every ping fails and incurs the overhead of establishing a new connection. If there's a consistent problem with leaving an open connection then that will be happening far more often than your Pre would poll a POP server, and that's when your battery gets sucked. Unfortunately there's probably nothing that you can do about it since the mail server and the infrastructure between you and it is likely out of your control.

    If so, then you're pretty much stuck switching to POP, but that doesn't mean that all IMAP idle is bad...
    Last edited by ktessner; 04/06/2010 at 02:51 PM.
    Yeah, uhh... it's Kevin. (KevinT was already taken.)

    PalmPilot Professional, Palm V, Kyocera 7135, Treo 600, Treo 650, Treo 700p, Palm Prē & Prē 2, HP TouchPad & Veer
  5. aaronpaul's Avatar
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    My IMAP works great with push. I have two accounts using it and have no noticeable difference in battery life. I use as my web/email host...

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