Check that the destination is specified
correctly.
See "Sending Internet Faxes without
Using SMTP Server", User Guide (HTML).
Creating a shared folder on the
destination computer. To check the folder
name, select the destination in the
address book, press [Edit], and see "Path"
in [Destinations] tab [Folder].
See "Transferring a Received Fax
Document to E-mail Address or Folder",
User Guide (HTML).