attaching file with email from some other server (URL) ? pleaes guide

In an Asp.net page I am sending emails with attachments. Issue is the files to attach are stored on some other server. Please guide how to attach such a file. I tried to give URL of file but got error "URI formats are not supported." Please guide me how to attach file from other server.

Message.Attachments.Add(new Attachment("http://domain.com/upload/cv.doc")); ...