Category: WMV Export Component
Subject: Mail Attachments
By default, Macintosh Mail (as well as some other Mail Clients) assumes your recipient is also a Mac user and therefore includes the resource forks (if any) of attached files. Normally a Mac user sees such attachments as a single file, whereas a Windows user sees two individual files - one containing the data fork of the file and the other containing the resource fork.
One way to avoid this is to choose "Windows Friendly" attachments, Mail strips the resource fork so that Windows users receive just one file, not two (one of which would be unusable anyway). In most cases - at least for files created with modern applications - all the crucial parts of files are in the data fork; as long as the filename has the correct extension and they have an appropriate application, Windows users can open the file.
To tell Mail to use Windows Friendly encoding for all new messages, choose Edit > Attachments > Always Send Windows Friendly Attachments. (Although this command appears on a menu, it's actually saved as a preference.) Oddly, this command is disabled when composing a new message.
You can also toggle Windows friendliness for individual messages: When you attach a file using the Attach button on the toolbar or by choosing File > Attach File (Command-Shift-A), notice the checkbox at the bottom, Use Windows Friendly Attachments. If it's selected, all the attachments for this particular message are sent in Windows Friendly format. Unfortunately, Mail offers no convenient way to toggle Windows friendliness for attachments added to your message by drag & drop or copy & paste.