When trying to send mail by Netscape, this message is displayed. Netscape is trying to save the outbound message to a file that has been specified by the user, but does not exist.
To correct this problem do the following: go to options Mail and News Preferences, then go to Compose. A template pops up. There is a section that specifies where to save outgoing mail and news files. Make sure that these files exist or remove them from the template, if you do not care about logging which messages are sent through Netscape.