Default format for "mail recipient as attachment" emails
 

This has been bugging me forever and I can't find a solution anywhere.

If I email a spreadsheet to someone using "File / Send to / mail recipient
(as attachment)", the default format for the email is Plain Text. EVERY TIME
I use this method to send a spreadsheet (and I do it a lot), I have to change
the format from Plain Text to HTML, then change the style to Normal.

In my Outlook options, HTML is set as the default format, and I have no
problems when sending emails using Outlook.

The same problem occurs with MS Word ... but not with Powerpoint.

I was beginning to think there wasn't a solution, but I just tried the "mail
recipient (as attachment)" thing on a colleague's computer, and the format
was HTML! So there HAS to be a solution. He and I tried to figure out what
was different in the settings on our two machines, but no luck.

Please help - thanks!