IBM released version 1.7 of the IBM Connections mail plugin. If you have installed Connections 5.5 then you need to use that version.
IBM Connections 5.5: File Upload via HTTP Server (Documentation error)
If you try to configure file upload via HTTP server in Connections 5.5 as described in the infocenter, you will get an error similar to this if you try to start the HTTP server afterwards: httpd: Syntax error on line