Mail using LARGE amount of space

I was looking at my fiances hard drive and trying to clear up some space for her, ran daisydisk and it said that there was 144.8GB used for mail, and only 180GB used on the drive. When I open the library up to look into it I get to "Recovered messages" in that folder are 4 other folders ( it was either 4 or 5, I'm trying to remember off the top of my head, I don't have it in front of me at the moment.). The biggest on is 50GB and when I open it it has a bunch of files, and each one that I click takes me back to the same email in her MAIL application. What I want to know is is it ok if I delete all of these files or will I mess anything up? If they are all leading back to the same email I would think it would be safe to delete them and the only thing I'd lose is that particular email. Thanks for the input guys.