I'm dealing with a problem regarding an email that was sent out by someone who claims he didn't send it out. Does anyone know if it's possible to send out an email using the Exchange administrator account, and for all practical purposes make it appear as if the user sent it out? I'm referring to the message appearing in the sent items folder, and everything in the header appears to be a normal message? This mailbox has no delegates configured and no send-as or other permissions. We know it was sent from a Windows machine with Outlook based on the CLientType in the Exchange logs. This administrator account has been used to migrate from the internal Exchange server to Office 365.
Thank you.