System requirements Windows 2000 Server or Advanced Server Microsoft Exchange server 2000 To receive messages from users sending mails in Exchange 5.5 RTF format: Microsoft Outlook 2000 OR the Windows Messaging components installed on the Mail essentials machine. Note that Microsoft Outlook must be set as the default mail client! Make sure Outlook express does not set itself as the default mail client. The Windows 2000 messaging components are supplied by Microsoft, but can be downloaded from the GFI Mail essentials support page. For more information http://support.microsoft.com/support/kb/articles/Q254/4/58.ASP If you install Mail essentials purely to protect your network from email viruses & email attacks & harmless or useless attachments, then you don't need to re-configure anything on your network. You simply have to run Mail essentials set-up