The resource fork holds information about the windows, dialog boxes, images, etc. used by the application. Once the resource fork is trashed, the application is dead.

The best way to transfer a Mac app and keep its resource fork is to use StuffIt to binhex or just stuff the file before sending via email, ftp, or burning to a CD that doesn't maintain the resources.

If you can get the file stuffed, and then FTP it again, you should have a working application. Burn the stuffed file to CD, and then instruct your end user to un-stuff it at their end. StuffIt Expander is available as a free download