Rationality isn't just about being skeptical, though, and there is something to be said for giving people the benefit of the doubt and engaging with them if they are willing to do so in an open manner. There are obviously limits to the extend to which you want to do so, but so far this thread has been an interesting read so I wouldn't worry to much about us wasting our time.
Recently, multiple suspicious user accounts were created on Less Wrong. These accounts don't post any content in the forum. Instead, they are used only to send private messages to the existing users.
Many users have received a copy of the same message, but different variants exist, too. Here are the examples I know about. If you have received a different variant, please post it in a comment below this article:
I don't know yet about anyone who replied and got scammed, so this is all based on indirect evidence. If you got scammed, please tell me. If you are ashamed, I can publish your story anonymously. Your story could help other potential victims.
Most likely, the scheme is the following:
(Thanks to ChristianKl for explaining the system in the Open Thread.)
If you replied to the original message and now you are already in the middle of the process, please inform your bank as soon as possible! Even if the step 2 didn't happen yet, so you can still get out without losing money, warning your bank about the scammer could help other potential victims.
Warning: If you have already received a check or a payment confirmation, and someone is asking you to send the overpayment back quickly, do not send anything. The check or the payment confirmation is fake, and the goal is to make you send money before you find out. (Thanks to qsz for explaining.)