Recently someone whom I more or less trust (let's call him John) showed me a screenshot of an email from someone else (let's call him Paul). It was bad and if it's true then it means Paul is bad person. These were screenshots showing this opened email from Paul to John. It looked like this was sent using MAXHERO program/extension or someting similar so it could not be read again after you once opened it.
Paul is claiming he never sent an email to John. John is claiming that it was self-destruct email and it disappered from his inbox once he opened it. Paul read something about this MXHERO service and he told me that the content of the letter could disapper because it is on mxhero's server the email itself should stay in John's inbox and even if he sent it to him, once it was delivered it would stay there. He is also claiming that he could get this email from different address and easily manipulate the screenshot so it would show his adress. Paul is using Gmail and John is using hotmail.
Is it possible that the email itself deleted from John's inbox (he does not want to show me this though...)?