Microsoft considers .gif
images to be active content, and for security reasons, Outlook does not allow active content to run in messages.
All Outlook versions after 2007
There is no support for animated gif-files when composing or reading an email. If you want to see the animation you’ll need to open the message in a browser.
To do this, double click the message to open it in its own window. Then choose (Other) Actions-> View in Browser. This will open the message in Internet Explorer.
Note: Even though the gif-file will not animate while composing, when the recipient receives your message in a mail client that does support gif-animation, the gif-animation will still work.
Source
So what this is saying is that Outlook will show the first frame of a .gif
image. If you add a .gif
using compose email in Outlook, and send the email to a device that can display .gif
, say an iPhone, the .gif
will animate on there.
In Outlook versions before 2007 they have limited support. This is because in 2007 Microsoft moved from using Internet Explorer (which can display .gif
) to render the emails, to Microsoft Word (which blocks .gif
).
Because of this change, Outlook does not support a lot of the latest HTML5 standards, including the HTML5 animations. So there is currently no way for Outlook (desktop at least) to show any type of animation.