You are technically correct, e-mails aren’t judicially approved. They are hearsay, a statement made outside of court. They absolutely can be used as evidence. Lionel Hutz was on the money when he said that ‘hearsay is a kind of evidence’. Depending on the hearsay it can be quite strong evidence. That evidence can be used to make a testimony and that is judicially approved. There is strong hearsay, such as a series of emails which details the crime, and there is weak hearsay, like ‘everyone knows Joe did it’. One of those examples of hearsay you can take to court, the other, well you can take what everyone is saying to court but it won’t get you very far.