Apple iPhone iOS 5.1 - Manual (Page 71)

Fetch New Data
This setting lets you turn Push on or off for iCloud, Microsoft Exchange, Yahoo!, and any other push
accounts on iPhone. Push accounts deliver new information to iPhone whenever new information
appears on the server (some delays may occur) and there’s an Internet connection. You might want
to turn Push off to suspend delivery of email and other information, or to conserve battery life.
When Push is off, and with accounts that don’t support push, data can still be fetched—that
is, iPhone can check with the server to see if new information is available. Use the Fetch New
Data setting to determine how often data is requested. For optimal battery life, don’t fetch too
often. Setting Push to OFF (or setting Fetch to Manually on the Fetch New Data screen) overrides
individual account settings.
Set Push settings: Go to Settings > Mail, Contacts, Calendars > Fetch New Data.
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