Animated GIFs
You can include an animated GIF image in campaign content just like any other image, however unfortunately Outlook (2007 and newer) will only display the first frame. To date, Outlook 365 as well as Outlook mobile apps and Webmail also do not support animated GIFs.
We recommend ensuring the first frame of your animated GIF includes all of the key information you are trying to convey, in the event the animated GIF does not display. You can also review which email clients your audience is using to help determine the potential impact.
See also: Litmus Guide to Animated GIFs and Animated GIF Support