I have a CFO client who received an email in his inbox, according to the headers it was from the CEO asking to pay a $35k invoice (NOW) the email appeared to quote a previous email that had never been sent or received by those on it and included a pdf invoice with information that was accurate about a customer/vendor and product details.

The email has a header that shows it came through Smartermail from the CEO to the CFO. the previous quoted email is not in the mailboxes of those listed, neither does it show in the gateway SMTP logs or Smartermail SMTP or administrative logs. The message ID on the email is not found when doing a Smartermail message ID search??

Can anyone explain how an email can show up in a users mailbox when the message ID cannot be found and the sender does not have it in their sent items..??