I put it all in the ad - criteria and info about the property, including negatives (no dishwashers, no balconies, showers but no tubs, small parking lot and street parking, no elevator - but well maintained in good location, etc.), then went over it all before a showing.Kids are more destructive than pets.  

If you wanted to be extra safe, you could also try mailing it to the address they just vacated and hope that they have their mail forwarded to their correct address.But at this point, I would just do exactly what @Dawn Anastasi suggested and keep the returned envelope still sealed with the check inside, along with the email documentation of your attempts to contact them, and let it go until they contact you.  

I currently have white appliances in there ( fridge and dishwasher are only a couple months new).

If you're worried about water, aside from buying non-pressboard vanities, you can also seal the exposed edges of the vanity with a polyurethane (learned this trick from countertop installers who do it underneath the counter where the dishwasher and sink go), set it on a waterproof base/pedestal, or just replace it when it starts to warp and rot. 

Been there, done that with the stoves and cooktops, refrigerator and dishwasher.

And then I focus prospective residents on the new stainless fridge, not the 7 year old white dishwasher. 

No food disposals or dishwashers.  

Never even dawned on me that we could get a break on our insurance until I read this post though! 

Dawn Brenengen Thanks for the reply.

I don't like disposals but yes to the dishwasher.