Sure, you could say the same of any document, electronic or not. Most crime is not that complicated.

  It turns out that the metadata footprint left on a computer creating a document- if you can seize it- is rich in detail enabling creation date and the like to be identified. Mail servers may hold logs. Often a fake email or document is part of an offense and proving where a faked email was sent from becomes quite relevant, and yes, ends up as evidence in court.

You may hear a prosecutor say "and on the 30th of june 2011 did you send the following email..blah..blah"

There is a reason for that- they are establishing the possibility that it is actually evidence. Its not clear cut, otherwise we wouldn't have courts. You proffer evidence and convince people of it's weight. And that will continue to be the case.