If you are having trouble connecting to your email server, the first thing you should do is check your underlying Internet connection, for example by surfing some web pages you haven't visited in awhile, to make sure it really is a problem with your email. If you are setting up your email application for the first time or have recently changed your configuration, then also double-check your configuration settings, especially the server names, email address, and user name, since this is the most common cause of email connection problems.

The actual cause can be either a worm virus (run immediately your anti-virus) or the so-called spoofing: a spammer pretending to be you employing your address name. As it's quite difficult to avoid this kind of problem, you should consider to get an email authentication.