Sorry, I guess I missed the email part. That is solely a notification you have a PM on the MOC forum. While you can see the text in the email, you have to go to the forum and logon in order to respond.
The "Home" screen that you see when you logon and any subsequent screens always have a link to read PMs. Click on the "Private Messages" link circled in red in the picture below. That will take you to the screens I posted earlier where you can read and reply to the PM.
