If I don't receive a tax bill, who's fault is it?

Hello, My mother ped away in 08. I never thought of paying her real estate taxes last year. I was at my mother's house daily remodeling it. Apparently the mailman knew no one was living at the house and didn't leave the real estate tax bills that are in BOTH my mother's and my name. Shouldn't the mailman or the courthouse forwarded the tax bill to MY residence? I'm uming the bill went back to the sender? Since my name was listed on the envelope beneath my mothers shouldn't they have forwarded the bills to my residence. The people I'm now renting my mother's house to gave me the tax bill that states I owe like $200 in late penalties that they just received. No one was living at the house when these taxes were due so I know someone just didn't ignore them. Any suggestions? Ideas? I called the courthouse and they pretty much said," too bad". Thanks! Jack