fxp is the traffic between two ftp servers, sending there files direct to each other.
an example:
open flashfxp or windows commander on a client
in the left window connect the sme server, on the right also.
now try to copy or move things from one ftp instance to the
other. that does not work, since sme only supports ftp (client > server)
uploads/downloads and not fxp (server > server) uploads/downloads
(which easyly would work if fxp is enabled).
i think it´s turned off for security reasons.
love&light
Metin