If you're accessing VSys using RD Web, RemoteApp or Remote Desktop, and you want to add attachments to someone, drag & drop doesn't work; that's a limitation of Remote Desktop, not VSys. What you can do, though, is magic!
On your local machine, in Windows Explorer, right-click on the file(s) you want to attach and click on Copy. This copies the file to the Windows Clipboard.
In VSys One, right-click in the attached files tool above, and select Paste files from clipboard. Depending on the size of the files and the speed of your connection this could take a while, but VSys will add the file(s) to this person without your having to first save them to the machine where VSys One is actually running, and without your trying to find the files via a mapped drive.