Is it a scam to send things by SF Express and sign for them by SMS password? Or do people I know don't want to recognize the courier I know?

Generally speaking, no. At present, express delivery usually puts parcels at pick-up points such as express cabinets or post offices. After receiving the package, the courier and the pick-up point will send you a short message through their respective short message systems. Short messages usually contain passwords (numeric and random alphabetic codes). You can use this password to pick up your package at the express cabinet and the pick-up point. The system and staff can also use this password to find your package from a pile of express delivery more quickly, which is normal operation.

However, it does not rule out that criminals use this to send fraudulent text messages to commit fraud. It is recommended to pay more attention. Operations involving payment, etc. shall be terminated immediately and reported to the public security organ.

Please adopt it if it is useful.