An email can be filtered, doing that with a subpoena would be... silly. > a really stupid waste of time and resources Subpoenas are used all the time in cases

An email can be filtered, doing that with a subpoena would be... silly. > a really stupid waste of time and resources Subpoenas are used all the time in cases where they're not expected to be inherently useful for acquiring information. If law enforcement is going to take 10x as long to find the perp because you hid them, I don't see a problem with them sharing that burden with you a bit—there are externalities here that should be internalized.