Where does inactive users pull data from?

I found C:\Program Files (x86)\SmarterTools\SmarterMail\Service\LastLoginTimes.xml, but several accounts listed on the inactive users page don't show up in this file. I'm writing a script to see the total disk usage for our inactive accounts and I was using the LastLoginTimes.xml file as a reference. Then I noticed the account discrepancy. So is there another file that inactive users pulls from?

I'm on SmarterMail 14.4.5801.