This raises a bunch of red flags (also confirmed by googling the email address it came from), but I don't quite understand how this scam is actually supposed to work. So, here it goes:
I put up an ad (for a guitar, 90€) on LeBonCoin (the French equivalent of Craigslist).
Someone contacts me by text message (anonymous with no actual phone number), saying they want to continue by email.
I then get an email, with roughly the following content (rough translation):
OK, I will buy it, but I need to send you cash by "express DHL letter". The DHL driver will pick up the item when he gives you the cash. I need the following information: full name, postal address, price of the item, and your phone number.
I'm guessing that this works by them requesting some "delivery fee" in advance, but does anyone know how this actually works?