Your best protection from fraud is your own precautions and gut feel. We strongly recommend you contact the Owner by phone, Skype, WhatsApp or something similar, especially when finalizing your arrangements. Email communications are not genuine and sufficient enough to verify you are dealing with a reputable Owner. Verbal cues are only second to face to face communications in determining the sincerity of the person you are dealing with. Ask for many details about the property. These will only be known by true the Owner/Agent of a property.
Never deal with an Owner who will not talk to you on the phone. If they have access to email, they can certainly talk to you on the phone. Contact them more than once over a period of time.
Ask for referrals. Search for comments on the internet. Search for their phone number on the internet. Are they members of a Better Business Bureau or Tourist Board?