The easiest thing to do is check the email address. If you're supposedly getting a job offer from your city government, the email address should be "cityofchicago.gov" or "chicago.gov" or something. If the address doesn't make sense, it's probably a scam. The other thing you can do is check the spelling. If you're getting an email about a job offer at "Amason.com," it's probably not legit.