I'm pretty certain that you're off topic for this forum, which is dedicated to Windows Live OneCare. You may want to try the Microsoft Public newsgroups here: http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx
No matter if you are off topic or on topic, you're not providing much information to go by. What email program? When are you getting this? Are you trying to access your email for your ISP, Hotmail, etc? Is it an error you get when checking your email? I suspect that you are getting this message when checking your ISP email via POP and you probably need to contact your ISP for help.
-steve