can't find 110gb from MAIL app that appear in manage space function

Macbook pro 2011, updated ram and single state hard drive- When my machine is out of hard drive space and the manage space option pops up. It shows you the line graph of what is filling up your machine. system is this many gigs, music is this many gigs and so on up to 100% of your machine. Well on that graph for my cpu, there is 110 gbs for the MAIL app. I have gone through my laptop file by file to try and find this 110gb of mail. I have deleted everything in the mail app to the point where it's not even setup anymore. When I open the mail app it wants me to pick an email provider to add. I tried deleting the actual Mail app but it wont let me. I was about to try cleanmymac to see if it would find the phantom mail files, but I googled reviews for cmm and this forum came up telling me not to use it. So I thought I would try making a post in the forum instead. Has anyone had a similar problem? Is there any reputable software out there that could help me find and clean these phantom files? This is 1/5 of my hard drive space that is not usable. thank you for any help!