If MS Outlook is your email client...............

Most likely because you are sending in "Rich Text Format"

Change to "Plain Text" and the problem will(should) go away.


Gord Dibben Excel MVP

On Mon, 28 Nov 2005 07:51:02 -0800, "kym_596"
wrote:

When I send Emails to clients with a spreadsheet attached the files are
changed from .xls to .dat. Why does this happen?