How can I use the files modification date & time without MDTM or MFMT support?
If your FTP server does not support setting the files last modification date & time (either by using the MFMT or MDTM commands, or via the SITE UTIME command) then SyncBackFree/SE/Pro can change the local source files last modification date & time to match that of the file on the FTP server if that might help (it will not do so by default, but you can select the option "If the FTP server cannot set a files date & time then change the local files date & time to match that on the server" on the main FTP settings page).
SyncBackFree does not support the MFMT or SITE UTIME commands (it only supports setting a files date & time on an FTP server using the MDTM command).
See the FAQ question How do you know if a file has been modified on an FTP server? for more information: