First turn on the Common Sense.
If the owner/landlord can not show you the rental and or if they ask for you to send money = scam.
If they are asking a crazy low price = scam
Do a google search of the address, many homes for sale are taken and converted to a rental that is not real. The listed home will usually not also be listed as a rental so start asking questions.
Is there an owner or agent you can call? There should be and they will be able to show you the house, not mail you keys.