Wrong content-type for XHTML files attachment in Apple Mail

For archive, to have an URI for this bug report.
sent by http://www.apple.com/feedback/mail.html

Example of attachment here

Hi,

I would to notify a bug which can be reproduced. I'm using Apple Mail  
Version 3.2 (919/919.2).
When sending a foo.xhtml (XHTML) file in attachment, the Content-Type  
sent along with the attachment is "application/octet-stream" instead  
of "application/xhtml+xml". It creates issues with archiving system  
trusting the content type sent with the mail.


--Apple-Mail-3--367791545
Content-Disposition: attachment;
	filename=foo.xhtml
Content-Type: application/octet-stream;
	x-unix-mode=0644;
	name="2-minutes.xhtml"
Content-Transfer-Encoding: 7bit


Best Regards.
-- 
Karl Dubost - W3C
http://www.w3.org/QA/
Be Strict To Be Cool