Police said the mailers are fake and residents should call police if they receive one.
In a separate scam, a man identified himself as a city employee and told a resident the city's water supply was contaminated and that he needed to come in to conduct tests.
Authorities warn residents to ask for identification before letting someone into their homes.
Residents may call the city's water services division at (714) 741-5395 if they have any doubt about a city employee's identity.
