Policy is created to block uploads on free file transfer sites that are listed in a custom Gatelet.
Free file transfer sites like the following:
filetransfer.io
fex.net
transfernow.net
sendfiles.net
Some file transfer sites process an upload differently and will create a link for a download before confirming the upload succeeded.
Depending on the file transfer site, some sites show the upload is successful, but then the link to download the file does not work. Test to verify the upload did or did not work by downloading it or sending the file via email through the file transfer site. If the download link does not work on the email will not send, then the file block was successful.