Thank you for the input, it wasn't those types of issues which I checked first. I got past this by creating a new user and migrating the user data, and everything looks good now user the new account.
Thank you, thread can be closed.
I've read a lot of different posts on the question mark issue but this one is different. I migrated a user account to a new one (created new account, made this one administrator, moved folder contents, removed old account). When the Mail application runs, the html in the emails shows as lots of...