We'd be happy to share more information on this with you! At this time GIFs are not animated in certain email clients. More specifically Outlook 2007, 2010 and 2013 won’t show the animation. Instead, they will show the first frame. I apologize for any inconvenience this causes. We also have this article from our help center that goes over using animated GIF images in your emails as well.
The animated gif I inserted appears distorted in Outlook. The animation works, but the image is stretched. How can I fix this?
We're sorry to hear that your gif is being distorted in Outlook. This can sometimes happen due to the way Outlook interprets code compared to other email clients.
I'd recommend utilizing this article on manually resizing your image inside the Library (as opposed to the email editor). Specifically look in the section for After Uploading to the Library. Do note that most of our templates are 620px wide, so you'll want to lock the resolution and set the width to a number that makes sense for how much of the email's with you want it to span.
Please let us know whether or not this resolves the issue for you, so we can make sure to update our service request notes accordingly.