This is what I can find and not post specific details that are covered by privacy concerns.
First there are no logs of member changes of email addresses.
The system does show me the IP used by a member when they joined the forum, as well as the IP used for each post. MP's IP identification was the same that last post andd in posts I could check quickly bu searching threads started by member search; and that IP was not the IP used by MP when MP joined the foum.
The most recent post from 4 days go is not the same as the one used when MP joined this forum, It is the same as other recents posts, though.
There is a feature to send an email to a member through the forum, which is logged. So you might want to use it to send an email, and we can see if MP responds. (Click on send e-mail through his member profile.)