• Tap Settings on the iPhone Home screen.
  • Select Mail, Contacts, Calendars.
  • Tap the desired Exchange account under Accounts.
  • Now tap Mail Days to Sync.
  • Pick how many recent days' mail you want to be sent to iPhone Mail automatically.
    • Choose No Limit to synchronize all mail.
    • Note that there is no way to see or search messages older than the synchronization limit.
  • Press the Home button.