Its a scam.

What they do is give you a certified check or MO for over the amount of the asking price. So your sell your item for $100 they give you $200. Then they want you to cash the MO and keep a $100 and give their "mover" $100 cash

The problem is the CC or MO is almost always fake and it takes a couple of weeks for your bank to figure that out.

So you give cash to the "mover" and your on the hook for the fake CC or MO. and owe the bank the full amount.

Forward the email and the attorney general and craigslist.