Yup, I was troubled by this phenomenon shortly after BT and Yahoo had their bust-up about 15 months ago. Suddenly my host started being blacklisted in several places, and btinternet started bouncing my mails on my main email address. Fortunately I also had a btintnernet.com email, so could get stuff out. Only solved in my case by changing my hosting company; this prob is not an option in your case?