.docx works for me in 5.0.2 NE. I don't have any .xlsx or .pptx files. "view as html" works too.
Zimbra trusts the MIME type sent by the client. If the webmail user or RFC822 message responsible for getting the attachment to Zimbra in the first place tagged it with the wrong MIME type, then the wrong MIME type will be reported by ZWC at download time. .docx should be Content-Type: application/vnd.openxmlformats-officedocument.wordprocessingml.document |