The impact of Push e-mail on battery life is, in I believe, dependent on the volume/frequency of e-mail you receive. If you receive a lot of e-mail throughout the day, turning of push e-mail and just periodically checking it (either manually or through preset pull times) will help battery life. If, on the other hand, you don't receive e-mails often, better to keep push turned on.

I have several e-mail accounts on my iPhone. For those those accounts that receive a lot of e-mails, I have push turned off. For those accounts that only receive e-mail infrequently, I have push turned on. This seems to work well for me.

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-Jay
The Fine Print:Nothing in this post (or any of my other posts) is intended to constitute legal advice or the establishment of an attorney-client relationship. For purposes of this forum, I'm just another nerd like you. :-)