Email attachment type

[#1]

Its not a big problem, but one of my colleagues uses a Mac, and every email she sends with an attachment is described as a Flash Video in the Evolution email client on Ubuntu, regardless of the actual file type. This means when I click on it, it tries to open in the media player, which clearly doesn't work if the attachment is a spreadsheet. It is not a big problem, as I just save the files elsewhere before opening them.
In the source of the email is this, just before the attachment,

Content-type: video/x-flv; name="xxxxxxxxx.xls"

So I assume the problem is with the way the attachment is reported by the Mac, but why would it report all attachments as Flash Videos?

[#2]

Have you tried renaming the file to the correct extension and then opening it?

[#3]

but XLS is the extension for a spreadsheet
is it that the Mac user is storing them in a Video folder?

[#4]

No idea, I'll have to ask!

[#5]

    *  To make files you attach to all outgoing messages "Windows-friendly," choose Edit > Attachments > Always Send Windows Friendly Attachments. To attach a Windows-friendly file to a single message, click Send Windows Friendly Attachments in the Attach dialog for that message.
      If you send attachments to Mac users with the "Windows-friendly" option selected, your attachment may be unusable or may be missing information (such as the preview icon for the file).
    * Use filename extensions, such as .doc, in the names of files you send to Windows recipients. This way the files can be read by a Windows application.