Hi Glenn,
The email from "Mariana" is, as you say, a scam. I couldn't work out the point of it when I received those emails last year, so I played along for a while…we got as far as her heading to Moscow to catch a plane to Australia, before I gave up out of boredom. I believe the scam was going to involve me sending her money so that she catch a plane to Australia.
I'm about to start the process again with an alias and follow through until I get a definitive answer as to what the scam is.
Regards,
Samuel Gordon-Stewart
Canberra