Increase root disk usage available after extending ext4 patition, Emails bouncing due to disk full errors

Hello everyone, Just upgrade to Webmin 1.921/virtualmin 1.771 along with multiple other updates, including new Debian 10 image 4.19.37-5+deb10u2. So really not sure what's the culprit. Started getting errors in email of 'not enough disk space' and looked over logs to determine it was the logs itself over utilizing space. Reset both mail.log and mail.info with "> /var/log/mail.xxxx" and that cleared up 4G of space. Still a bit more disk usage than I would anticipate Webmin/virtualmin needing to operate (15G available from 20G drive). This is on a VMware esxi VM. Increased disk size to 50 gig, then expanded it in Debian from the previous 20G, so fdisk shows 50G available on primary/root partition, but Webmin still shows same 15G available in both dashboard and under System> Disk and Network Filesystems> / (Root Filesystem). Already noticing the amount available reducing quickly. This is effecting my emails greatly along with CPU usage at 90-100% constantly, thus vm running much slower than normal and emails either taking hours to be delivered; if delivered at all. Can't even email myself and get it to any email in my own domain instantly like I used to.

Seems my domain has also got blacklisted by gmail in the same instance (not that it's necessarily related). Just email has just become a huge drain on my time during one the most busy times of year and haven't seemed to find the solution as I would normally besides old bugs that keep saying they've been fixed and closed with no solution besides it's fixed in next update which were years ago. Most documentation gives old interface as well, so it's confusing where I should find some of the options or are not working as they specify in forums/documentation.

How do I go about changing webmin to permission use of this additional extended space I just created to help alleviate disk usage pressure so I can get emails going without having this issue in a short order again? Any help would be appreciated, thanks in advance.

-dan