Mail app taking up lots of space

I'm trying to clean up my Mac storage, and my mail app is taking up 1.3 GB of my available space. When I open the app, I have no emails to delete at all. I honestly just want to delete the app since I only use Gmail, but since that isn't allowed, I was wondering what steps I could take to make it take up less space. I've never used it before so I don't know why it's using so much of my storage!