Well.. lets see, if JB logged in and left his e-mail up, a cleaning person could have responded :-)
Then there is "spoofing", done that with my boss, which came "from" her boss but was me, telling my Boss that Doug is an outstanding employee and should be considered for a raise.
Hey, I am sure that the e-mails were from the "man", but nowadays, pinging addresses, only tells you "where" it was originated from, does not tell you who actually wrote it.