uploading to a different server via CFFILE?

When you define any Windows service, one of the "properties" of that service is the definition of the account that it is to log-on as.

(See:  Administrative Tools .. Services.  Choose a service, right click, choose Properties.  From the pop-up, choose the Log On tab.  Your Windows version may vary.)

By default, services tend to log on as the "Local System account," which probably isn't what you want, I think, for something like CF.  Not if it has the ability to interact with local files, e.g. uploading and downloading.  It is far better in my opinion for you to define a local account ... one that is not capable of being "logged on" to ... whose only purpose is for it to be used by the CF Server.  This will allow you to build a definite boundary around what the CF Server can do, and it will also let you easily identify the files that are created by the server.  The so-called "principle of least privilege" is a good bright-line rule to follow, and when CF is being used to manipulate files (locally and/or elsewhere), I think it's prudent to give CF its own explicit identity.

You can use cffile to upload to any server to which you have the required permission.  I forget the exact syntax, but it's probably something like

\\server name\drive\path\file name