I am concerned that running constantly on 3G or Wifi drains my battery too much so i dont even check my email on iphone because i dont want to keep checking my sbsettings...is there an app/addon so that the iphone connects occasionaly and downloads/sends...and then disconnects, like lets say every 5 mins.

Also, can i setup something so that iphone goes online when i start the mail app or the browser...?