Email problem?

I had checked my mail on my daughters computer while visiting her.When I checked my mail the next day,on my computer, I had over 500 emails from someone's address which were in my inbox.Now,most of the mail said,"mailer-daemon" cannot deliever .It was addressed to some individuals address,but came in my mail.I wrote this person an email,and guess where it went,thats right,to me.I tried to delete some of the email,and it would only add more to my box.I emailed yahoo,with the problem,and heard nothing.I don't know what to do.This morning I had over 689 emails from this particular address.Can I eliminate my address on yahoo for good,and start another one.The problem is I really don't want to,so many people and companys have my address that I couldn't remember them all.I'm so caught up in this problem with no where to turn.Any thoughts out there...............And by the way,I do mark them as spam,but continue to receive this persona mail