Not supported.
See http://msdn2.microsoft.com/en-us/library/aa338201.aspx

Signature
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
-----
> I want to sent an html mail from my web application with a gradient
> effect,but in outlook 2007 its not showing the gradient effect with this
> html
> code DXImageTransform.Microsoft.gradient
FCA - 31 Mar 2008 11:47 GMT
Is any other way for the gredient effect ather than the image
> Not supported.
> See http://msdn2.microsoft.com/en-us/library/aa338201.aspx
[quoted text clipped - 3 lines]
> > html
> > code DXImageTransform.Microsoft.gradient
Roady [MVP] - 31 Mar 2008 12:04 GMT
Pre-process the image instead of altering it at run-time.

Signature
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
-----
> Is any other way for the gredient effect ather than the image
>
[quoted text clipped - 6 lines]
>> > html
>> > code DXImageTransform.Microsoft.gradient
FCA - 31 Mar 2008 12:20 GMT
Thank you Mr. Roady
> Pre-process the image instead of altering it at run-time.
>
[quoted text clipped - 8 lines]
> >> > html
> >> > code DXImageTransform.Microsoft.gradient
Roady [MVP] - 31 Mar 2008 13:20 GMT
You're welcome! :-)

Signature
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
-----
> Thank you Mr. Roady
>
[quoted text clipped - 10 lines]
>> >> > html
>> >> > code DXImageTransform.Microsoft.gradient