I am subscribed to the Litmus's newsletters (litmus.com) and more than once I have been surprised by the animated gifs included in their emails.
They even have a very recommendable publication on their blog about how to include and optimize animated gifs in emails, although it's about animated gifs in general: https://litmus.com/blog/a-guide-to-animated-gifs-in-email.
From there I extract this text:
Not everyone has Photoshop chops, though. Many marketers and designers need to make GIFs out of existing video footage. While you could use something like Adobe After Effects, tools exist for most platforms that make GIF creation easy. On Mac, many people swear by GIF Brewery. Windows users can take advantage of programs like Instagiffer and GIF Animator. If you’re looking for online tools, there is no shortage of web-based GIF creators. There are even apps on mobile that can help you create GIFs!
Beyond Photoshop, I think Adobe After Effects has better animation resources.