Yes you can!
The way to have an animated promo banner in your email signature is to upload your banner as an animated GIF when adding your promo banner to Mirosign. This is the only format possible because this is the only format that will display in most recipients email applications.
What email programs send animated GIFs?
So far we’ve found them to work when sending from Gmail, Outlook 2013, Apple Mail, iPhone and iPad.
What email programs show animated GIFs?
Nearly all of the major email clients can now show animated GIFs, however older versions of Outlook do not support animated GIFs
Older versions of Outlook such as Outlook 2007, Outlook 2010 , Outlook 2013 and Outlook 2016 do not support animated GIFs so you’ll want to ensure the first frame of your animated image shows your important content so these users still can see it.
Microsoft 365 and Office 2021
Playing and inserting animated GIFs in emails is fully supported when you use Outlook as part of a Microsoft 365 subscription or Office 2021.
The GIF-animation will not loop indefinitely but will only loop 3 times. After 3 animation loops, the animation will stop and a Play button will show on the image. Pressing this Play button will loop the animation another 3 times.
for more information see here Making GIFs animate