Last year, Joseph Dixon* posted a picture of himself on Instagram, tagging it #T-Mobile, the company he works for as a store manager. The photo gathered a fair amount of likes, and also got the attention of someone who had an unusual business proposal.

"Do you wanna make some money?" the person—a would-be scammer—wrote in an Instagram private message, according to Dixon. (*Dixon's name has been changed because he was not authorized by T-Mobile to speak to the press.)