There were some dead giveaways in the September 4th email: the wording was rough, and the capitalization and punctuation were poor. Scammers seldom speak the Queen's English.
Having said that ... whenever I receive a request to perform an action on a Sedo sale, I
always log into my Sedo account and make sure that the progress of the transaction is correctly reflected there, before I make the payment or push the domain.
Good luck, glad to hear that Moniker seems to have things under control for you!
P.S. Sedo has been around a long time, and they have a much smaller Moniker account number than the one in that letter!
