Ever want to convey something but an image won't cut it?
Audiences pay attention 88% more when viewing a video (or gif) instead of an image, so why not give it a shot?
GIFs also have a faster load time so when someone opens your email is will have a higher likely hood of being ready to display.
Suggested Use Case
My favorite use case is a GIF from a video you want your users to watch, here is an example; which are you more likely to click?
Might not be the fairest comparison, however, it gets the point across, you're eye will go to the thing in motion before the standstill image.
Biggest Concern: "GIFs aren't professional, they're childish" Not long ago the thought of including an image that wasn't a logo into an email we "unprofessional" this thought process was quickly dismissed when marketers saw their click rates skyrocket.
I always suggest "Brand Appropriate" GIFs, i.e., If you're a wedding photography company maybe you include a gif of photos being captured at a wedding.
Of course, you should always think about your age demographic; if your demographic is 25 or below as a majority, GIFs might not be a bad thing to try.
I will always recommend that you do a trial period, test out sending something with a GIF to 20% of your audience in a cluster sampling method. Then use a calculation like this;
Previous Click Percent from the most recent campaign (decimal): X
Percent of your audience you're sending it out to (decimal): Y
New Click Rate from the new audience (decimal): Z
(X÷Y) - Z = How well this did.
Using this will help you decide whether GIFs work well for your audience.
Please note: I am not taking into account of how an ISP would read the email.