This is an unofficial web site that cannot be used to contact Michael Cretu. Your best chance is probably to try his management company or music label, although it's a good idea to keep in mind that he has many fans and could not possibly respond to everyone. Crocodile Music in Germany is the management company, and they have a contact page. Enigma also has some pages on the German EMI Music site. It used to be Virgin Schallplatten in Germany that acted as a label for Enigma, but they were consolidated into EMI who now releases the albums.
If you would like to contact the person behind this web site, please send your e-mail to firstname.lastname@example.org and it will reach me. I don't always have time to reply right away, but your comments are definitely appreciated. English messages are your best bet, as I only know a few languages besides that.