We could use some more information. What Email tool are you using. Outlook? How do you connect to your provider? Pop3 setup? And by stay in ip box, do you mean that you can't load them to your machine, or that they don't disappear from the isp's server when you do?
My best guesses are that either you need to reconfigure your new instance of Outlook to connect to the provider (it has a test button to poke the config and see what fails), or that you are using a port number that is blocked. But more details are needed.