What do you do if you need evidence from a client? You ask for it. If it is more than a couple of current emails, you need to raise the flag about preserving the evidence in a way that most corporate IT departments do not know how to do. You and your client need to involve a certified forensic examiner and get them to produce that data for you. Simply accessing data can corrupt it and sabotage evidence that may be needed for your case or in a courtroom setting.
