Definitely a trick to posting on craigslist. You want to avoid people who are trying to scam you because there will be some like that. Do not respond to any emails you get via craigslist where they don’t specify exactly what it is you’re selling. For example they say “do you still have it? Do you still have these?”
I put in my ads “serious inquiries only. Only emails with contact information will be answered.”
If someone asks for a code or something of this nature, you need to ignore them, that’s also a scam.
Always arrange to meet in a neutral area for example a gas station or supermarket parking lot. Do not give people your address.