He claims to be spooked by the confidentiality notice attached to the bottom of emails from Mark. But that notice doesn't say any of the information is confidential, it just says what the penalties are for breaking a confidentiality agreement. The notice is boilerplate, people who use it automatically attach it to all emails. It is not specific to that email or anything in it.
And how do you know if any information in the email is confidential and therefore covered by that notice? Easy--if it is the subject of a prior agreement to keep it confidential, then it applies.
No prior agreement, no confidentiality. Period.