Based on waht you are saying, it can be a scam.

It had happened to me once when I posted one of my rental property on Retgurs University Off-Camps Housing Service website, I had received an email from UK, that person said want to rent my place and would send me the deposit by money order, but the person hadn't mail me the money order which the deadline I had given to him/her. Soon after I had sent him/her an email to notify him/her that my place is no longer available, I had received yhe money order the amount was much higher than the deposit he/she should paid. Then I got an email from him/her and asked me to cash the money order and send the money back to the address she/he gave to me through e-transfer. I had deposited the money order but didn't transfer the money out right away. Next day, I went to my bank to get the cash and wanted to do e-transfer, I has found that my back have freezed my account because the money order is not real.