Make sure you use the option in the Save As dialog to include filename
extensions so it's sent as myfile.docx, but that may not be enough.
You also need to be certain that your email program is set to use the
correct encoding for attachments. Exact phrasing varies from one email
client to another, but if you're using Entourage you'll find it in
Entourage> Preferences - Compose... Use the encoding option for Windows
(MIME/Base64). If you're using Apple's Mail app you'll find it in Edit>
Attachments> Always send Windows Friendly Attachments.
It's also possible that either your email service or (more likely) the
recipient's server (Exchange or 'free' web mail by any chance?) is
mishandling the attachment. If the above steps don't resolve the problem zip
the file before attaching... Which is not a bad habit to get into, anyway.
HTH |:>)
Bob Jones
[MVP] Office:Mac