I managed to install mattermost, and it works great for now.
We use it in my team to replace the mails.
But something we heavily used in our mails are GIFs, but they don’t autoplay in chat. It basically looks like this :
I think it could be great to add it as an option.
Something else that would be great is the ability to import an image directly from a link. I’m not very clear, but to see what I mean, you can install the giphy in chrome and try to import a gif directly