Scammers are now sending USPS WhatsApp scam messages similar to text messages. USPS doesn't send WhatsApp messages. The scam messages are similar to texts with a link that goes to a phishing website that steals account credentials. Or, contains a telephone number that recipients are asked to call. But, instead of calling USPS, they will be connected to a call center operated by scammers, whose job is to trick potential victims into disclosing their account personal and financial information.
If the requested information is given to the scammers, they will use it fraudulently.