Small Excel file that causes this issue
test.xlsx (application/vnd.openxmlformats-officedocument.spreadsheetml.sheet), 11.06 KB, created by Bryan on 2011-08-05 14:47:52 UTC
Creator: Bryan
Created: 2011-08-05 14:47:52 UTC
Size: 11.06 KB

Attachment is not viewable in your browser because its MIME type (application/vnd.openxmlformats-officedocument.spreadsheetml.sheet) is not one that your browser is able to display.

Download the attachment.

Actions: View
Attachments on bug 51626: 27355 | 29301