I am not sure I understand what the issue here is? Subscribe your mail service to a range of RBL's. Don't use one, use many. If you ARE on a dynamic IP address, make sure your provider has a secure SMTP Auth relay server for you to use and tunnel ALL of your outbound through this smart host. Sure a few lines extra of configuration, but weeks at a time of lowered frustration. There are many stringent reasons for blocking mail, if you had to choose the RFC Ignorant RBL, you would be blocking ALL mail from Germany and South Africa (among others). Why? Becuae the whois services provided by their ccTLD's do not follow strictly the whois RFC. Whats that got to do with mail? Nothing. But there are people who use these lists. So make sure you keep your very own headache levels down by accepting the fact that the world we live in is NOT a nice place and that you have to take certain measures that others will be taking for granted.