As the description of the error indicates, the application (typically an email client) has problems connecting to the server (the mail server). This could indicate connectivity problems (network, firewalls, Internet), problems with the remote server (can you access it from a different application?), a problem with the application itself or interference from other applications (proxy clients, antivirus software). In one instance, a user was able to connect to his mail server with Outlook Express but not with Outlook 2000 (even though it used to work before and no changes were made to the configuration). In this case, the problem went away when the Norton Antivirus running on that machine was stopped.
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