Never mind. I found the answer myself.
The animated graphic in my e-mail message doesn't work
Symptoms
When you receive an e-mail message that contains animated graphics, such as animated .gif files, only a static image appears.
Cause
Microsoft Office Outlook 2007 does not display animated graphics files in the body of e-mail messages. Only the first frame of the animation appears.
Resolution
You can view the message in your Web browser to see the animation.
View an e-mail message in your Web browser
Open the message.
On the Message tab, in the Actions group, click Other Actions.
Click View in Browser