Why when I require SSL connections for FTP 7.5 the client computer is unable to access the site (534-Policy requires SSL: this is the error shown by Mozilla Firefox)?

Hi, Firefox does not natively support FTP/SSL, but there is an add-on available for it. See http://linux.derkeiler.com/Newsgroups/comp.os.linux.misc/2006-08/msg00320.html https://addons.mozilla.org/en-US/firefox/addon/684/ -- Mike Burr

Even Internet Explorer is unable to access the FTP site.

I installed the firefox module and it changed nothing. I tried ftps://x.x.x.x

Don't you have any suggestion?

I'd recommend asking here for IE and the SFTP site, you are likely to get an expert, http://forums.iis.net/ You may want to try here for the Firefox add-in, http://www.mozilla.org/community/forums/ -- Mike Burr